diff --git a/library/aes.c b/library/aes.c
index 7a44a78..1eb3e20 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -386,7 +386,7 @@
     {
         pow[i] = x;
         log[x] = i;
-        x = ( x ^ XTIME( x ) ) & 0xFF;
+        x = MBEDTLS_BYTE_0( x ^ XTIME( x ) );
     }
 
     /*
@@ -395,7 +395,7 @@
     for( i = 0, x = 1; i < 10; i++ )
     {
         RCON[i] = (uint32_t) x;
-        x = XTIME( x ) & 0xFF;
+        x = MBEDTLS_BYTE_0( XTIME( x ) );
     }
 
     /*
@@ -408,10 +408,10 @@
     {
         x = pow[255 - log[i]];
 
-        y  = x; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
-        x ^= y; y = ( ( y << 1 ) | ( y >> 7 ) ) & 0xFF;
+        y  = x; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
+        x ^= y; y = MBEDTLS_BYTE_0( ( y << 1 ) | ( y >> 7 ) );
         x ^= y ^ 0x63;
 
         FSb[i] = (unsigned char) x;
@@ -424,8 +424,8 @@
     for( i = 0; i < 256; i++ )
     {
         x = FSb[i];
-        y = XTIME( x ) & 0xFF;
-        z =  ( y ^ x ) & 0xFF;
+        y = MBEDTLS_BYTE_0( XTIME( x ) );
+        z = MBEDTLS_BYTE_0( y ^ x );
 
         FT0[i] = ( (uint32_t) y       ) ^
                  ( (uint32_t) x <<  8 ) ^
@@ -577,10 +577,10 @@
             for( i = 0; i < 10; i++, RK += 4 )
             {
                 RK[4]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[3] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[3] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[3] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[3]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[3] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[3] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[3] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[3] ) ] << 24 );
 
                 RK[5]  = RK[1] ^ RK[4];
                 RK[6]  = RK[2] ^ RK[5];
@@ -593,10 +593,10 @@
             for( i = 0; i < 8; i++, RK += 6 )
             {
                 RK[6]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[5] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[5] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[5] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[5]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[5] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[5] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[5] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[5] ) ] << 24 );
 
                 RK[7]  = RK[1] ^ RK[6];
                 RK[8]  = RK[2] ^ RK[7];
@@ -611,20 +611,20 @@
             for( i = 0; i < 7; i++, RK += 8 )
             {
                 RK[8]  = RK[0] ^ RCON[i] ^
-                ( (uint32_t) FSb[ ( RK[7] >>  8 ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[7] >> 16 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[7] >> 24 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[7]       ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[7] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[7] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[7] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[7] ) ] << 24 );
 
                 RK[9]  = RK[1] ^ RK[8];
                 RK[10] = RK[2] ^ RK[9];
                 RK[11] = RK[3] ^ RK[10];
 
                 RK[12] = RK[4] ^
-                ( (uint32_t) FSb[ ( RK[11]       ) & 0xFF ]       ) ^
-                ( (uint32_t) FSb[ ( RK[11] >>  8 ) & 0xFF ] <<  8 ) ^
-                ( (uint32_t) FSb[ ( RK[11] >> 16 ) & 0xFF ] << 16 ) ^
-                ( (uint32_t) FSb[ ( RK[11] >> 24 ) & 0xFF ] << 24 );
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_0( RK[11] ) ]       ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_1( RK[11] ) ] <<  8 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_2( RK[11] ) ] << 16 ) ^
+                ( (uint32_t) FSb[ MBEDTLS_BYTE_3( RK[11] ) ] << 24 );
 
                 RK[13] = RK[5] ^ RK[12];
                 RK[14] = RK[6] ^ RK[13];
@@ -690,10 +690,10 @@
     {
         for( j = 0; j < 4; j++, SK++ )
         {
-            *RK++ = AES_RT0( FSb[ ( *SK       ) & 0xFF ] ) ^
-                    AES_RT1( FSb[ ( *SK >>  8 ) & 0xFF ] ) ^
-                    AES_RT2( FSb[ ( *SK >> 16 ) & 0xFF ] ) ^
-                    AES_RT3( FSb[ ( *SK >> 24 ) & 0xFF ] );
+            *RK++ = AES_RT0( FSb[ MBEDTLS_BYTE_0( *SK ) ] ) ^
+                    AES_RT1( FSb[ MBEDTLS_BYTE_1( *SK ) ] ) ^
+                    AES_RT2( FSb[ MBEDTLS_BYTE_2( *SK ) ] ) ^
+                    AES_RT3( FSb[ MBEDTLS_BYTE_3( *SK ) ] );
         }
     }
 
@@ -786,52 +786,52 @@
 }
 #endif /* MBEDTLS_CIPHER_MODE_XTS */
 
-#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                     \
-    do                                                          \
-    {                                                           \
-        (X0) = *RK++ ^ AES_FT0( ( (Y0)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y1) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y2) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y3) >> 24 ) & 0xFF );        \
-                                                                \
-        (X1) = *RK++ ^ AES_FT0( ( (Y1)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y2) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y3) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y0) >> 24 ) & 0xFF );        \
-                                                                \
-        (X2) = *RK++ ^ AES_FT0( ( (Y2)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y3) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y0) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y1) >> 24 ) & 0xFF );        \
-                                                                \
-        (X3) = *RK++ ^ AES_FT0( ( (Y3)       ) & 0xFF ) ^       \
-                       AES_FT1( ( (Y0) >>  8 ) & 0xFF ) ^       \
-                       AES_FT2( ( (Y1) >> 16 ) & 0xFF ) ^       \
-                       AES_FT3( ( (Y2) >> 24 ) & 0xFF );        \
+#define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                 \
+    do                                                      \
+    {                                                       \
+        (X0) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y0 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y1 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y2 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y3 ) );     \
+                                                            \
+        (X1) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y1 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y2 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y3 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y0 ) );     \
+                                                            \
+        (X2) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y2 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y3 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y0 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y1 ) );     \
+                                                            \
+        (X3) = *RK++ ^ AES_FT0( MBEDTLS_BYTE_0( Y3 ) ) ^    \
+                       AES_FT1( MBEDTLS_BYTE_1( Y0 ) ) ^    \
+                       AES_FT2( MBEDTLS_BYTE_2( Y1 ) ) ^    \
+                       AES_FT3( MBEDTLS_BYTE_3( Y2 ) );     \
     } while( 0 )
 
 #define AES_RROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)                 \
     do                                                      \
     {                                                       \
-        (X0) = *RK++ ^ AES_RT0( ( (Y0)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y3) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y2) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y1) >> 24 ) & 0xFF );    \
+        (X0) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y0 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y3 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y2 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y1 ) );     \
                                                             \
-        (X1) = *RK++ ^ AES_RT0( ( (Y1)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y0) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y3) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y2) >> 24 ) & 0xFF );    \
+        (X1) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y1 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y0 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y3 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y2 ) );     \
                                                             \
-        (X2) = *RK++ ^ AES_RT0( ( (Y2)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y1) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y0) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y3) >> 24 ) & 0xFF );    \
+        (X2) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y2 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y1 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y0 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y3 ) );     \
                                                             \
-        (X3) = *RK++ ^ AES_RT0( ( (Y3)       ) & 0xFF ) ^   \
-                       AES_RT1( ( (Y2) >>  8 ) & 0xFF ) ^   \
-                       AES_RT2( ( (Y1) >> 16 ) & 0xFF ) ^   \
-                       AES_RT3( ( (Y0) >> 24 ) & 0xFF );    \
+        (X3) = *RK++ ^ AES_RT0( MBEDTLS_BYTE_0( Y3 ) ) ^    \
+                       AES_RT1( MBEDTLS_BYTE_1( Y2 ) ) ^    \
+                       AES_RT2( MBEDTLS_BYTE_2( Y1 ) ) ^    \
+                       AES_RT3( MBEDTLS_BYTE_3( Y0 ) );     \
     } while( 0 )
 
 /*
@@ -864,28 +864,28 @@
     AES_FROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] );
 
     t.X[0] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[0]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[0] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[1] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[2] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[3] ) ] << 24 );
 
     t.X[1] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[1]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[1] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[2] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[3] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[0] ) ] << 24 );
 
     t.X[2] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[2]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[3] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[2] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[3] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[0] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[1] ) ] << 24 );
 
     t.X[3] = *RK++ ^ \
-            ( (uint32_t) FSb[ ( t.Y[3]       ) & 0xFF ]       ) ^
-            ( (uint32_t) FSb[ ( t.Y[0] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) FSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) FSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_0( t.Y[3] ) ]       ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_1( t.Y[0] ) ] <<  8 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_2( t.Y[1] ) ] << 16 ) ^
+            ( (uint32_t) FSb[ MBEDTLS_BYTE_3( t.Y[2] ) ] << 24 );
 
     MBEDTLS_PUT_UINT32_LE( t.X[0], output,  0 );
     MBEDTLS_PUT_UINT32_LE( t.X[1], output,  4 );
@@ -928,28 +928,28 @@
     AES_RROUND( t.Y[0], t.Y[1], t.Y[2], t.Y[3], t.X[0], t.X[1], t.X[2], t.X[3] );
 
     t.X[0] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[0]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[0] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[3] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[2] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[1] ) ] << 24 );
 
     t.X[1] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[1]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[1] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[0] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[3] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[2] ) ] << 24 );
 
     t.X[2] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[2]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[3] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[2] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[1] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[0] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[3] ) ] << 24 );
 
     t.X[3] = *RK++ ^ \
-            ( (uint32_t) RSb[ ( t.Y[3]       ) & 0xFF ]       ) ^
-            ( (uint32_t) RSb[ ( t.Y[2] >>  8 ) & 0xFF ] <<  8 ) ^
-            ( (uint32_t) RSb[ ( t.Y[1] >> 16 ) & 0xFF ] << 16 ) ^
-            ( (uint32_t) RSb[ ( t.Y[0] >> 24 ) & 0xFF ] << 24 );
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_0( t.Y[3] ) ]       ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_1( t.Y[2] ) ] <<  8 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_2( t.Y[1] ) ] << 16 ) ^
+            ( (uint32_t) RSb[ MBEDTLS_BYTE_3( t.Y[0] ) ] << 24 );
 
     MBEDTLS_PUT_UINT32_LE( t.X[0], output,  0 );
     MBEDTLS_PUT_UINT32_LE( t.X[1], output,  4 );
diff --git a/library/aria.c b/library/aria.c
index 320f775..6bfdfbd 100644
--- a/library/aria.c
+++ b/library/aria.c
@@ -212,22 +212,22 @@
                             const uint8_t sa[256], const uint8_t sb[256],
                             const uint8_t sc[256], const uint8_t sd[256] )
 {
-    *a = ( (uint32_t) sa[ *a        & 0xFF]       ) ^
-         (((uint32_t) sb[(*a >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*a >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *a >> 24        ]) << 24);
-    *b = ( (uint32_t) sa[ *b        & 0xFF]       ) ^
-         (((uint32_t) sb[(*b >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*b >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *b >> 24        ]) << 24);
-    *c = ( (uint32_t) sa[ *c        & 0xFF]       ) ^
-         (((uint32_t) sb[(*c >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*c >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *c >> 24        ]) << 24);
-    *d = ( (uint32_t) sa[ *d        & 0xFF]       ) ^
-         (((uint32_t) sb[(*d >>  8) & 0xFF]) <<  8) ^
-         (((uint32_t) sc[(*d >> 16) & 0xFF]) << 16) ^
-         (((uint32_t) sd[ *d >> 24        ]) << 24);
+    *a = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *a ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *a ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *a ) ]) << 16) ^
+         (((uint32_t) sd[ *a >> 24             ]) << 24);
+    *b = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *b ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *b ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *b ) ]) << 16) ^
+         (((uint32_t) sd[ *b >> 24             ]) << 24);
+    *c = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *c ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *c ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *c ) ]) << 16) ^
+         (((uint32_t) sd[ *c >> 24             ]) << 24);
+    *d = ( (uint32_t) sa[ MBEDTLS_BYTE_0( *d ) ]       ) ^
+         (((uint32_t) sb[ MBEDTLS_BYTE_1( *d ) ]) <<  8) ^
+         (((uint32_t) sc[ MBEDTLS_BYTE_2( *d ) ]) << 16) ^
+         (((uint32_t) sd[ *d >> 24             ]) << 24);
 }
 
 /*
diff --git a/library/asn1write.c b/library/asn1write.c
index 0289e89..8555767 100644
--- a/library/asn1write.c
+++ b/library/asn1write.c
@@ -60,8 +60,8 @@
         if( *p - start < 3 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
+        *--(*p) = MBEDTLS_CHAR_0( len );
+        *--(*p) = MBEDTLS_CHAR_1( len );
         *--(*p) = 0x82;
         return( 3 );
     }
@@ -71,9 +71,9 @@
         if( *p - start < 4 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
-        *--(*p) = ( len >> 16 ) & 0xFF;
+        *--(*p) = MBEDTLS_CHAR_0( len );
+        *--(*p) = MBEDTLS_CHAR_1( len );
+        *--(*p) = MBEDTLS_CHAR_2( len );
         *--(*p) = 0x83;
         return( 4 );
     }
@@ -85,10 +85,10 @@
         if( *p - start < 5 )
             return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
 
-        *--(*p) = ( len       ) & 0xFF;
-        *--(*p) = ( len >>  8 ) & 0xFF;
-        *--(*p) = ( len >> 16 ) & 0xFF;
-        *--(*p) = ( len >> 24 ) & 0xFF;
+        *--(*p) = MBEDTLS_CHAR_0( len );
+        *--(*p) = MBEDTLS_CHAR_1( len );
+        *--(*p) = MBEDTLS_CHAR_2( len );
+        *--(*p) = MBEDTLS_CHAR_3( len );
         *--(*p) = 0x84;
         return( 5 );
     }
diff --git a/library/camellia.c b/library/camellia.c
index 4d6b468..29d730a 100644
--- a/library/camellia.c
+++ b/library/camellia.c
@@ -278,14 +278,14 @@
     I0 = x[0] ^ k[0];
     I1 = x[1] ^ k[1];
 
-    I0 = ((uint32_t) SBOX1((I0 >> 24) & 0xFF) << 24) |
-         ((uint32_t) SBOX2((I0 >> 16) & 0xFF) << 16) |
-         ((uint32_t) SBOX3((I0 >>  8) & 0xFF) <<  8) |
-         ((uint32_t) SBOX4((I0      ) & 0xFF)      );
-    I1 = ((uint32_t) SBOX2((I1 >> 24) & 0xFF) << 24) |
-         ((uint32_t) SBOX3((I1 >> 16) & 0xFF) << 16) |
-         ((uint32_t) SBOX4((I1 >>  8) & 0xFF) <<  8) |
-         ((uint32_t) SBOX1((I1      ) & 0xFF)      );
+    I0 = ((uint32_t) SBOX1( MBEDTLS_BYTE_3( I0 )) << 24) |
+         ((uint32_t) SBOX2( MBEDTLS_BYTE_2( I0 )) << 16) |
+         ((uint32_t) SBOX3( MBEDTLS_BYTE_1( I0 )) <<  8) |
+         ((uint32_t) SBOX4( MBEDTLS_BYTE_0( I0 ))      );
+    I1 = ((uint32_t) SBOX2( MBEDTLS_BYTE_3( I1 )) << 24) |
+         ((uint32_t) SBOX3( MBEDTLS_BYTE_2( I1 )) << 16) |
+         ((uint32_t) SBOX4( MBEDTLS_BYTE_1( I1 )) <<  8) |
+         ((uint32_t) SBOX1( MBEDTLS_BYTE_0( I1 ))      );
 
     I0 ^= (I1 << 8) | (I1 >> 24);
     I1 ^= (I0 << 16) | (I0 >> 16);
diff --git a/library/ccm.c b/library/ccm.c
index 424ee77..95d90dc 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -200,7 +200,7 @@
     memcpy( b + 1, iv, iv_len );
 
     for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
-        b[15-i] = (unsigned char)( len_left & 0xFF );
+        b[15-i] = MBEDTLS_CHAR_0( len_left );
 
     if( len_left > 0 )
         return( MBEDTLS_ERR_CCM_BAD_INPUT );
@@ -221,8 +221,8 @@
         src = add;
 
         memset( b, 0, 16 );
-        b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
-        b[1] = (unsigned char)( ( add_len      ) & 0xFF );
+        b[0] = MBEDTLS_CHAR_1( add_len );
+        b[1] = MBEDTLS_CHAR_0( add_len );
 
         use_len = len_left < 16 - 2 ? len_left : 16 - 2;
         memcpy( b + 2, src, use_len );
diff --git a/library/common.h b/library/common.h
index 4ecc016..56c3002 100644
--- a/library/common.h
+++ b/library/common.h
@@ -77,6 +77,15 @@
 #define MBEDTLS_BYTE_2( x ) ( (uint8_t) ( ( ( x ) >> 16 ) & 0xff ) )
 #define MBEDTLS_BYTE_3( x ) ( (uint8_t) ( ( ( x ) >> 24 ) & 0xff ) )
 
+#define MBEDTLS_CHAR_0( x ) ( (unsigned char) (   ( x )         & 0xff ) )
+#define MBEDTLS_CHAR_1( x ) ( (unsigned char) ( ( ( x ) >> 8  ) & 0xff ) )
+#define MBEDTLS_CHAR_2( x ) ( (unsigned char) ( ( ( x ) >> 16 ) & 0xff ) )
+#define MBEDTLS_CHAR_3( x ) ( (unsigned char) ( ( ( x ) >> 24 ) & 0xff ) )
+#define MBEDTLS_CHAR_4( x ) ( (unsigned char) ( ( ( x ) >> 32 ) & 0xff ) )
+#define MBEDTLS_CHAR_5( x ) ( (unsigned char) ( ( ( x ) >> 40 ) & 0xff ) )
+#define MBEDTLS_CHAR_6( x ) ( (unsigned char) ( ( ( x ) >> 48 ) & 0xff ) )
+#define MBEDTLS_CHAR_7( x ) ( (unsigned char) ( ( ( x ) >> 56 ) & 0xff ) )
+
 /**
  * 32-bit integer manipulation GET macros (big endian)
  *
diff --git a/library/ecjpake.c b/library/ecjpake.c
index d229311..7305dfe 100644
--- a/library/ecjpake.c
+++ b/library/ecjpake.c
@@ -180,10 +180,10 @@
     if( ret != 0 )
         return( ret );
 
-    (*p)[0] = (unsigned char)( ( len >> 24 ) & 0xFF );
-    (*p)[1] = (unsigned char)( ( len >> 16 ) & 0xFF );
-    (*p)[2] = (unsigned char)( ( len >>  8 ) & 0xFF );
-    (*p)[3] = (unsigned char)( ( len       ) & 0xFF );
+    (*p)[0] = MBEDTLS_CHAR_3( len );
+    (*p)[1] = MBEDTLS_CHAR_2( len );
+    (*p)[2] = MBEDTLS_CHAR_1( len );
+    (*p)[3] = MBEDTLS_CHAR_0( len );
 
     *p += 4 + len;
 
@@ -223,10 +223,10 @@
     if( end - p < 4 )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
 
-    *p++ = (unsigned char)( ( id_len >> 24 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len >> 16 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len >>  8 ) & 0xFF );
-    *p++ = (unsigned char)( ( id_len       ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_3( id_len );
+    *p++ = MBEDTLS_CHAR_2( id_len );
+    *p++ = MBEDTLS_CHAR_1( id_len );
+    *p++ = MBEDTLS_CHAR_0( id_len );
 
     if( end < p || (size_t)( end - p ) < id_len )
         return( MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL );
@@ -366,7 +366,7 @@
         goto cleanup;
     }
 
-    *(*p)++ = (unsigned char)( len & 0xFF );
+    *(*p)++ = MBEDTLS_CHAR_0( len );
     MBEDTLS_MPI_CHK( mbedtls_mpi_write_binary( &h, *p, len ) ); /* r */
     *p += len;
 
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 59c5460..7d65479 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -136,18 +136,18 @@
      * } ServerNameList;
      *
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SERVERNAME );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME );
 
-    *p++ = (unsigned char)( ( (hostname_len + 5) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 5)      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( hostname_len + 5);
+    *p++ = MBEDTLS_CHAR_0( hostname_len + 5);
 
-    *p++ = (unsigned char)( ( (hostname_len + 3) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( (hostname_len + 3)      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( hostname_len + 3 );
+    *p++ = MBEDTLS_CHAR_0( hostname_len + 3 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( hostname_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME );
+    *p++ = MBEDTLS_CHAR_1( hostname_len );
+    *p++ = MBEDTLS_CHAR_0( hostname_len );
 
     memcpy( p, ssl->hostname, hostname_len );
 
@@ -181,14 +181,12 @@
     /*
      * Secure renegotiation
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
     *p++ = 0x00;
-    *p++ = ( ssl->verify_data_len + 1 ) & 0xFF;
-    *p++ = ssl->verify_data_len & 0xFF;
+    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len + 1 );
+    *p++ = MBEDTLS_CHAR_0( ssl->verify_data_len );
 
     memcpy( p, ssl->own_verify_data, ssl->verify_data_len );
 
@@ -283,14 +281,14 @@
      * SignatureAndHashAlgorithm
      *   supported_signature_algorithms<2..2^16-2>;
      */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SIG_ALG      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SIG_ALG );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SIG_ALG );
 
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( sig_alg_len + 2 )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( sig_alg_len + 2 );
+    *p++ = MBEDTLS_CHAR_0( sig_alg_len + 2 );
 
-    *p++ = (unsigned char)( ( sig_alg_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( sig_alg_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( sig_alg_len );
+    *p++ = MBEDTLS_CHAR_0( sig_alg_len );
 
     *olen = 6 + sig_alg_len;
 
@@ -358,16 +356,14 @@
         elliptic_curve_list[elliptic_curve_len++] = info->tls_id & 0xFF;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_ELLIPTIC_CURVES );
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len + 2 )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len + 2 );
+    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len + 2 );
 
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ( elliptic_curve_len     )      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( elliptic_curve_len     );
+    *p++ = MBEDTLS_CHAR_0( elliptic_curve_len     );
 
     *olen = 6 + elliptic_curve_len;
 
@@ -388,10 +384,8 @@
         ( "client hello, adding supported_point_formats extension" ) );
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -427,8 +421,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     /*
      * We may need to send ClientHello multiple times for Hello verification.
@@ -470,8 +464,8 @@
         memcpy( p + 2, ssl->handshake->ecjpake_cache, kkpp_len );
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( kkpp_len );
+    *p++ = MBEDTLS_CHAR_0( kkpp_len );
 
     *olen = kkpp_len + 4;
 
@@ -510,11 +504,11 @@
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, (unsigned)( ssl->own_cid_len + 5 ) );
 
     /* Add extension ID + size */
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( ext_len );
+    *p++ = MBEDTLS_CHAR_0( ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -543,10 +537,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 5 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -577,8 +569,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -607,10 +599,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 )
-                            & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -641,11 +631,11 @@
     /* The addition is safe here since the ticket length is 16 bit. */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 + tlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
 
-    *p++ = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( tlen      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( tlen );
+    *p++ = MBEDTLS_CHAR_0( tlen );
 
     *olen = 4;
 
@@ -685,8 +675,8 @@
 
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 6 + alpnlen );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ALPN );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ALPN );
 
     /*
      * opaque ProtocolName<1..2^8-1>;
@@ -713,12 +703,12 @@
     *olen = p - buf;
 
     /* List length = olen - 2 (ext_type) - 2 (ext_len) - 2 (list_len) */
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    buf[4] = MBEDTLS_CHAR_1( *olen - 6 );
+    buf[5] = MBEDTLS_CHAR_0( *olen - 6 );
 
     /* Extension length = olen - 2 (ext_type) - 2 (ext_len) */
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    buf[2] = MBEDTLS_CHAR_1( *olen - 4 );
+    buf[3] = MBEDTLS_CHAR_0( *olen - 4 );
 
     return( 0 );
 }
@@ -770,12 +760,12 @@
      */
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, ext_len + 4 );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_USE_SRTP );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_USE_SRTP );
 
 
-    *p++ = (unsigned char)( ( ( ext_len & 0xFF00 ) >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ext_len & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( ext_len & 0xFF00 );
+    *p++ = MBEDTLS_CHAR_0( ext_len );
 
     /* protection profile length: 2*(ssl->conf->dtls_srtp_profile_list_len) */
     /* micro-optimization:
@@ -786,8 +776,7 @@
      *                        >> 8 ) & 0xFF );
      */
     *p++ = 0;
-    *p++ = (unsigned char)( ( 2 * ssl->conf->dtls_srtp_profile_list_len )
-                            & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( 2 * ssl->conf->dtls_srtp_profile_list_len );
 
     for( protection_profiles_index=0;
          protection_profiles_index < ssl->conf->dtls_srtp_profile_list_len;
@@ -799,8 +788,8 @@
         {
             MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_write_use_srtp_ext, add profile: %04x",
                                         profile_value ) );
-            *p++ = ( ( profile_value >> 8 ) & 0xFF );
-            *p++ = ( profile_value & 0xFF );
+            *p++ = MBEDTLS_BYTE_1( profile_value );
+            *p++ = MBEDTLS_BYTE_0( profile_value );
         }
         else
         {
@@ -1334,8 +1323,8 @@
     {
         /* No need to check for space here, because the extension
          * writing functions already took care of that. */
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_1( ext_len );
+        *p++ = MBEDTLS_CHAR_0( ext_len );
         p += ext_len;
     }
 
diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 77904e0..e0c50bc 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -454,15 +454,15 @@
         *cur = rec->cid_len;
         cur++;
 
-        cur[0] = ( ad_len_field >> 8 ) & 0xFF;
-        cur[1] = ( ad_len_field >> 0 ) & 0xFF;
+        cur[0] = MBEDTLS_CHAR_1( ad_len_field );
+        cur[1] = MBEDTLS_CHAR_0( ad_len_field );
         cur += 2;
     }
     else
 #endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
     {
-        cur[0] = ( ad_len_field >> 8 ) & 0xFF;
-        cur[1] = ( ad_len_field >> 0 ) & 0xFF;
+        cur[0] = MBEDTLS_CHAR_1( ad_len_field );
+        cur[1] = MBEDTLS_CHAR_0( ad_len_field );
         cur += 2;
     }
 
@@ -2481,8 +2481,8 @@
             /* Write message_seq and update it, except for HelloRequest */
             if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
             {
-                ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
-                ssl->out_msg[5] = ( ssl->handshake->out_msg_seq      ) & 0xFF;
+                ssl->out_msg[4] = MBEDTLS_CHAR_1( ssl->handshake->out_msg_seq );
+                ssl->out_msg[5] = MBEDTLS_CHAR_0( ssl->handshake->out_msg_seq );
                 ++( ssl->handshake->out_msg_seq );
             }
             else
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 3d67393..253ab56 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1848,8 +1848,8 @@
         for( j = 0, p = buf + ciph_offset + 2; j < ciph_len; j += 2, p += 2 )
             for( i = 0; ciphersuites[i] != 0; i++ )
             {
-                if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
-                    p[1] != ( ( ciphersuites[i]      ) & 0xFF ) )
+                if( p[0] != MBEDTLS_BYTE_1( ciphersuites[i] ) ||
+                    p[1] != MBEDTLS_BYTE_0( ciphersuites[i] ))
                     continue;
 
                 got_common_suite = 1;
@@ -1865,8 +1865,8 @@
         for( i = 0; ciphersuites[i] != 0; i++ )
             for( j = 0, p = buf + ciph_offset + 2; j < ciph_len; j += 2, p += 2 )
             {
-                if( p[0] != ( ( ciphersuites[i] >> 8 ) & 0xFF ) ||
-                    p[1] != ( ( ciphersuites[i]      ) & 0xFF ) )
+                if( p[0] != MBEDTLS_BYTE_1( ciphersuites[i] ) ||
+                    p[1] != MBEDTLS_BYTE_0( ciphersuites[i] ))
                     continue;
 
                 got_common_suite = 1;
@@ -1971,11 +1971,11 @@
      *   } ConnectionId;
     */
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_CID      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_CID );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_CID );
     ext_len = (size_t) ssl->own_cid_len + 1;
-    *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( ext_len );
+    *p++ = MBEDTLS_CHAR_0( ext_len );
 
     *p++ = (uint8_t) ssl->own_cid_len;
     memcpy( p, ssl->own_cid, ssl->own_cid_len );
@@ -2016,8 +2016,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding encrypt then mac extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2042,8 +2042,8 @@
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding extended master secret "
                         "extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2067,8 +2067,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, adding session ticket extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SESSION_TICKET      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SESSION_TICKET );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SESSION_TICKET );
 
     *p++ = 0x00;
     *p++ = 0x00;
@@ -2091,8 +2091,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, secure renegotiation extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_RENEGOTIATION_INFO );
 
 #if defined(MBEDTLS_SSL_RENEGOTIATION)
     if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
@@ -2132,8 +2132,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, max_fragment_length extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH );
 
     *p++ = 0x00;
     *p++ = 1;
@@ -2162,8 +2162,8 @@
 
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, supported_point_formats extension" ) );
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS );
 
     *p++ = 0x00;
     *p++ = 2;
@@ -2200,8 +2200,8 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_ECJPAKE_KKPP      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
+    *p++ = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ECJPAKE_KKPP );
 
     ret = mbedtls_ecjpake_write_round_one( &ssl->handshake->ecjpake_ctx,
                                         p + 2, end - p - 2, &kkpp_len,
@@ -2212,8 +2212,8 @@
         return;
     }
 
-    *p++ = (unsigned char)( ( kkpp_len >> 8 ) & 0xFF );
-    *p++ = (unsigned char)( ( kkpp_len      ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_1( kkpp_len );
+    *p++ = MBEDTLS_CHAR_0( kkpp_len );
 
     *olen = kkpp_len + 4;
 }
@@ -2238,18 +2238,18 @@
      * 6 . 6    protocol name length
      * 7 . 7+n  protocol name
      */
-    buf[0] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN >> 8 ) & 0xFF );
-    buf[1] = (unsigned char)( ( MBEDTLS_TLS_EXT_ALPN      ) & 0xFF );
+    buf[0] = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_ALPN );
+    buf[1] = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_ALPN );
 
     *olen = 7 + strlen( ssl->alpn_chosen );
 
-    buf[2] = (unsigned char)( ( ( *olen - 4 ) >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ( ( *olen - 4 )      ) & 0xFF );
+    buf[2] = MBEDTLS_CHAR_1( *olen - 4 );
+    buf[3] = MBEDTLS_CHAR_0( *olen - 4 );
 
-    buf[4] = (unsigned char)( ( ( *olen - 6 ) >> 8 ) & 0xFF );
-    buf[5] = (unsigned char)( ( ( *olen - 6 )      ) & 0xFF );
+    buf[4] = MBEDTLS_CHAR_1( *olen - 6 );
+    buf[5] = MBEDTLS_CHAR_0( *olen - 6 );
 
-    buf[6] = (unsigned char)( ( ( *olen - 7 )      ) & 0xFF );
+    buf[6] = MBEDTLS_CHAR_0( *olen - 7 );
 
     memcpy( buf + 7, ssl->alpn_chosen, *olen - 7 );
 }
@@ -2294,15 +2294,15 @@
     }
 
     /* extension */
-    buf[0] = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
-    buf[1] = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP      ) & 0xFF );
+    buf[0] = MBEDTLS_CHAR_1( MBEDTLS_TLS_EXT_USE_SRTP );
+    buf[1] = MBEDTLS_CHAR_0( MBEDTLS_TLS_EXT_USE_SRTP );
     /*
      * total length 5 and mki value: only one profile(2 bytes)
      *              and length(2 bytes) and srtp_mki  )
      */
     ext_len = 5 + mki_len;
-    buf[2] = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-    buf[3] = (unsigned char)( ext_len & 0xFF );
+    buf[2] = MBEDTLS_CHAR_1( ext_len );
+    buf[3] = MBEDTLS_CHAR_0( ext_len );
 
     /* protection profile length: 2 */
     buf[4] = 0x00;
@@ -2311,8 +2311,8 @@
                                 ssl->dtls_srtp_info.chosen_dtls_srtp_profile );
     if( profile_value != MBEDTLS_TLS_SRTP_UNSET )
     {
-        buf[6] = (unsigned char)( ( profile_value >> 8 ) & 0xFF );
-        buf[7] = (unsigned char)( profile_value & 0xFF );
+        buf[6] = MBEDTLS_CHAR_1( profile_value );
+        buf[7] = MBEDTLS_CHAR_0( profile_value );
     }
     else
     {
@@ -2648,8 +2648,8 @@
 
     if( ext_len > 0 )
     {
-        *p++ = (unsigned char)( ( ext_len >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ext_len      ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_1( ext_len );
+        *p++ = MBEDTLS_CHAR_0( ext_len );
         p += ext_len;
     }
 
@@ -3478,8 +3478,8 @@
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
     }
-    if( *p++ != ( ( len >> 8 ) & 0xFF ) ||
-        *p++ != ( ( len      ) & 0xFF ) )
+    if( *p++ != MBEDTLS_CHAR_1( len ) ||
+        *p++ != MBEDTLS_CHAR_0( len ) )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange message" ) );
         return( MBEDTLS_ERR_SSL_DECODE_ERROR );
@@ -4223,13 +4223,13 @@
         tlen = 0;
     }
 
-    ssl->out_msg[4] = ( lifetime >> 24 ) & 0xFF;
-    ssl->out_msg[5] = ( lifetime >> 16 ) & 0xFF;
-    ssl->out_msg[6] = ( lifetime >>  8 ) & 0xFF;
-    ssl->out_msg[7] = ( lifetime       ) & 0xFF;
+    ssl->out_msg[4] = MBEDTLS_CHAR_3( lifetime );
+    ssl->out_msg[5] = MBEDTLS_CHAR_2( lifetime );
+    ssl->out_msg[6] = MBEDTLS_CHAR_1( lifetime );
+    ssl->out_msg[7] = MBEDTLS_CHAR_0( lifetime );
 
-    ssl->out_msg[8] = (unsigned char)( ( tlen >> 8 ) & 0xFF );
-    ssl->out_msg[9] = (unsigned char)( ( tlen      ) & 0xFF );
+    ssl->out_msg[8] = MBEDTLS_CHAR_1( tlen );
+    ssl->out_msg[9] = MBEDTLS_CHAR_0( tlen );
 
     ssl->out_msglen = 10 + tlen;
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index f8cad4a..0655dc5 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -4582,8 +4582,8 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 8 ) & 0xFF,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 0 ) & 0xFF,
+    MBEDTLS_CHAR_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_CHAR_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
 };
 
 /*
@@ -4664,14 +4664,14 @@
     {
         start = (uint64_t) session->start;
 
-        *p++ = (unsigned char)( ( start >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( start >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( start       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_7( start );
+        *p++ = MBEDTLS_CHAR_6( start );
+        *p++ = MBEDTLS_CHAR_5( start );
+        *p++ = MBEDTLS_CHAR_4( start );
+        *p++ = MBEDTLS_CHAR_3( start );
+        *p++ = MBEDTLS_CHAR_2( start );
+        *p++ = MBEDTLS_CHAR_1( start );
+        *p++ = MBEDTLS_CHAR_0( start );
     }
 #endif /* MBEDTLS_HAVE_TIME */
 
@@ -4687,22 +4687,22 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session->ciphersuite >> 8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ciphersuite      ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_1( session->ciphersuite );
+        *p++ = MBEDTLS_CHAR_0( session->ciphersuite );
 
-        *p++ = (unsigned char)( session->compression & 0xFF );
+        *p++ = MBEDTLS_CHAR_0( session->compression );
 
-        *p++ = (unsigned char)( session->id_len & 0xFF );
+        *p++ = MBEDTLS_CHAR_0( session->id_len );
         memcpy( p, session->id, 32 );
         p += 32;
 
         memcpy( p, session->master, 48 );
         p += 48;
 
-        *p++ = (unsigned char)( ( session->verify_result >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->verify_result       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_3( session->verify_result );
+        *p++ = MBEDTLS_CHAR_2( session->verify_result );
+        *p++ = MBEDTLS_CHAR_1( session->verify_result );
+        *p++ = MBEDTLS_CHAR_0( session->verify_result );
     }
 
     /*
@@ -4719,9 +4719,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( cert_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( cert_len       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_2( cert_len );
+        *p++ = MBEDTLS_CHAR_1( cert_len );
+        *p++ = MBEDTLS_CHAR_0( cert_len );
 
         if( session->peer_cert != NULL )
         {
@@ -4762,9 +4762,9 @@
 
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session->ticket_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_len       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_2( session->ticket_len );
+        *p++ = MBEDTLS_CHAR_1( session->ticket_len );
+        *p++ = MBEDTLS_CHAR_0( session->ticket_len );
 
         if( session->ticket != NULL )
         {
@@ -4772,10 +4772,10 @@
             p += session->ticket_len;
         }
 
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session->ticket_lifetime       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_3( session->ticket_lifetime );
+        *p++ = MBEDTLS_CHAR_2( session->ticket_lifetime );
+        *p++ = MBEDTLS_CHAR_1( session->ticket_lifetime );
+        *p++ = MBEDTLS_CHAR_0( session->ticket_lifetime );
     }
 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
 
@@ -4793,7 +4793,7 @@
     used += 1;
 
     if( used <= buf_len )
-        *p++ = (unsigned char)( ( session->encrypt_then_mac ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_0( session->encrypt_then_mac );
 #endif
 
     return( used );
@@ -5568,11 +5568,11 @@
     MBEDTLS_VERSION_MAJOR,
     MBEDTLS_VERSION_MINOR,
     MBEDTLS_VERSION_PATCH,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 8 ) & 0xFF,
-    ( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG >> 0 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >> 16 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >>  8 ) & 0xFF,
-    ( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG >>  0 ) & 0xFF,
+    MBEDTLS_CHAR_1( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_CHAR_0( SSL_SERIALIZED_SESSION_CONFIG_BITFLAG ),
+    MBEDTLS_CHAR_2( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_CHAR_1( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
+    MBEDTLS_CHAR_0( SSL_SERIALIZED_CONTEXT_CONFIG_BITFLAG ),
 };
 
 /*
@@ -5713,10 +5713,10 @@
     used += 4 + session_len;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( session_len >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( session_len       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_3( session_len );
+        *p++ = MBEDTLS_CHAR_2( session_len );
+        *p++ = MBEDTLS_CHAR_1( session_len );
+        *p++ = MBEDTLS_CHAR_0( session_len );
 
         ret = ssl_session_save( ssl->session, 1,
                                 p, session_len, &session_len );
@@ -5757,33 +5757,33 @@
     used += 4;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->badmac_seen       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_3( ssl->badmac_seen );
+        *p++ = MBEDTLS_CHAR_2( ssl->badmac_seen );
+        *p++ = MBEDTLS_CHAR_1( ssl->badmac_seen );
+        *p++ = MBEDTLS_CHAR_0( ssl->badmac_seen );
     }
 
 #if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
     used += 16;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window_top       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_7( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_6( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_5( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_4( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_3( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_2( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_1( ssl->in_window_top );
+        *p++ = MBEDTLS_CHAR_0( ssl->in_window_top );
 
-        *p++ = (unsigned char)( ( ssl->in_window >> 56 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 48 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 40 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 32 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 24 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >> 16 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->in_window       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_7( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_6( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_5( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_4( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_3( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_2( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_1( ssl->in_window );
+        *p++ = MBEDTLS_CHAR_0( ssl->in_window );
     }
 #endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
 
@@ -5806,8 +5806,8 @@
     used += 2;
     if( used <= buf_len )
     {
-        *p++ = (unsigned char)( ( ssl->mtu >>  8 ) & 0xFF );
-        *p++ = (unsigned char)( ( ssl->mtu       ) & 0xFF );
+        *p++ = MBEDTLS_CHAR_1( ssl->mtu );
+        *p++ = MBEDTLS_CHAR_0( ssl->mtu );
     }
 #endif /* MBEDTLS_SSL_PROTO_DTLS */
 
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 902f99e..9e629cb 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -113,17 +113,17 @@
 #endif
 
     *p++ = 0;
-    *p++ = (unsigned char)( ( desired_length >> 0 ) & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( desired_length );
 
     /* Add label incl. prefix */
-    *p++ = (unsigned char)( total_label_len & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( total_label_len );
     memcpy( p, tls1_3_label_prefix, sizeof(tls1_3_label_prefix) );
     p += sizeof(tls1_3_label_prefix);
     memcpy( p, label, llen );
     p += llen;
 
     /* Add context value */
-    *p++ = (unsigned char)( clen & 0xFF );
+    *p++ = MBEDTLS_CHAR_0( clen );
     if( clen != 0 )
         memcpy( p, ctx, clen );