diff --git a/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
index f844561..320bb0e 100644
--- a/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
+++ b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
@@ -1,5 +1,6 @@
 Security
    * Zeroising of local buffers and variables which are used for calculations
-     in mbedtls_pkcs5_pbkdf2_hmac() and mbedtls_internal_sha*_process()
+     in mbedtls_pkcs5_pbkdf2_hmac(), mbedtls_internal_sha*_process(),
+     mbedtls_internal_md*_process() and mbedtls_internal_ripemd160_process()
      functions to erase sensitive data from memory. Reported by
      Johan Malmgren and Johan Uppman Bruce from Sectra.
diff --git a/library/md2.c b/library/md2.c
index 293ada3..eb4d0d0 100644
--- a/library/md2.c
+++ b/library/md2.c
@@ -181,6 +181,9 @@
         t  = ctx->cksum[i];
     }
 
+    /* Zeroise variables to clear sensitive data from memory. */
+    mbedtls_zeroize( &t, sizeof( t ) );
+
     return( 0 );
 }
 
diff --git a/library/md4.c b/library/md4.c
index 6982559..28e81c8 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -247,6 +247,13 @@
     ctx->state[2] += C;
     ctx->state[3] += D;
 
+    /* Zeroise variables to clear sensitive data from memory. */
+    mbedtls_zeroize( &X, sizeof( X ) );
+    mbedtls_zeroize( &A, sizeof( A ) );
+    mbedtls_zeroize( &B, sizeof( B ) );
+    mbedtls_zeroize( &C, sizeof( C ) );
+    mbedtls_zeroize( &D, sizeof( D ) );
+
     return( 0 );
 }
 
diff --git a/library/md5.c b/library/md5.c
index 009a013..9c75cae 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -266,6 +266,13 @@
     ctx->state[2] += C;
     ctx->state[3] += D;
 
+    /* Zeroise variables to clear sensitive data from memory. */
+    mbedtls_zeroize( &X, sizeof( X ) );
+    mbedtls_zeroize( &A, sizeof( A ) );
+    mbedtls_zeroize( &B, sizeof( B ) );
+    mbedtls_zeroize( &C, sizeof( C ) );
+    mbedtls_zeroize( &D, sizeof( D ) );
+
     return( 0 );
 }
 
diff --git a/library/ripemd160.c b/library/ripemd160.c
index aee1123..f585077 100644
--- a/library/ripemd160.c
+++ b/library/ripemd160.c
@@ -325,6 +325,19 @@
     ctx->state[4] = ctx->state[0] + B + Cp;
     ctx->state[0] = C;
 
+    /* Zeroise variables to clear sensitive data from memory. */
+    mbedtls_zeroize( &A, sizeof( A ) );
+    mbedtls_zeroize( &B, sizeof( B ) );
+    mbedtls_zeroize( &C, sizeof( C ) );
+    mbedtls_zeroize( &D, sizeof( D ) );
+    mbedtls_zeroize( &E, sizeof( E ) );
+    mbedtls_zeroize( &Ap, sizeof( Ap ) );
+    mbedtls_zeroize( &Bp, sizeof( Bp ) );
+    mbedtls_zeroize( &Cp, sizeof( Cp ) );
+    mbedtls_zeroize( &Dp, sizeof( Dp ) );
+    mbedtls_zeroize( &Ep, sizeof( Ep ) );
+    mbedtls_zeroize( &X, sizeof( X ) );
+
     return( 0 );
 }