diff --git a/programs/test/o_p_test.c b/programs/test/o_p_test.c
index eb02350..9726282 100644
--- a/programs/test/o_p_test.c
+++ b/programs/test/o_p_test.c
@@ -75,11 +75,12 @@
     unsigned char o_priv_encrypted[512];
     unsigned char p_priv_decrypted[512];
     unsigned char o_priv_decrypted[512];
-    char *pers = "o_p_test_example";
+    const char *pers = "o_p_test_example";
 
     entropy_init( &entropy );
     if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
-                    (unsigned char *) pers, strlen( pers ) ) ) != 0 )
+                    (const unsigned char *) pers,
+                    strlen( pers ) ) ) != 0 )
     {
         printf( " failed\n  ! ctr_drbg_init returned %d\n", ret );
         goto exit;
diff --git a/programs/test/ssl_cert_test.c b/programs/test/ssl_cert_test.c
index 57ea32c..83a2a01 100644
--- a/programs/test/ssl_cert_test.c
+++ b/programs/test/ssl_cert_test.c
@@ -41,7 +41,7 @@
 
 #define MAX_CLIENT_CERTS    8
 
-char *client_certificates[MAX_CLIENT_CERTS] =
+const char *client_certificates[MAX_CLIENT_CERTS] =
 {
     "client1.crt",
     "client2.crt",
@@ -53,7 +53,7 @@
     "cert_sha512.crt"
 };
 
-char *client_private_keys[MAX_CLIENT_CERTS] =
+const char *client_private_keys[MAX_CLIENT_CERTS] =
 {
     "client1.key",
     "client2.key",
diff --git a/programs/test/ssl_test.c b/programs/test/ssl_test.c
index 5d829e5..34fd9c2 100644
--- a/programs/test/ssl_test.c
+++ b/programs/test/ssl_test.c
@@ -74,7 +74,7 @@
 {
     int opmode;                 /* operation mode (client or server)    */
     int iomode;                 /* I/O mode (blocking or non-blocking)  */
-    char *server_name;          /* hostname of the server (client only) */
+    const char *server_name;    /* hostname of the server (client only) */
     int server_port;            /* port on which the ssl service runs   */
     int command;                /* what to do: read or write operation  */
     int buffer_size;            /* size of the send/receive buffer      */
@@ -153,7 +153,7 @@
     unsigned char *read_buf = NULL;
     unsigned char *write_buf = NULL;
 
-    char *pers = "ssl_test";
+    const char *pers = "ssl_test";
 
     struct hr_time t;
     entropy_context entropy;
@@ -166,7 +166,8 @@
 
     entropy_init( &entropy );
     if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
-                               (unsigned char *) pers, strlen( pers ) ) ) != 0 )
+                               (const unsigned char *) pers,
+                               strlen( pers ) ) ) != 0 )
     {
         printf( "  ! ctr_drbg_init returned %d\n", ret );
         goto exit;
@@ -204,7 +205,7 @@
         printf("POLARSSL_CERTS_C not defined.\n");
         goto exit;
 #else
-        ret =  x509parse_crt( &srvcert, (unsigned char *) test_srv_crt,
+        ret =  x509parse_crt( &srvcert, (const unsigned char *) test_srv_crt,
                               strlen( test_srv_crt ) );
         if( ret != 0 )
         {
@@ -212,7 +213,7 @@
             goto exit;
         }
 
-        ret =  x509parse_crt( &srvcert, (unsigned char *) test_ca_crt,
+        ret =  x509parse_crt( &srvcert, (const unsigned char *) test_ca_crt,
                               strlen( test_ca_crt ) );
         if( ret != 0 )
         {
@@ -220,7 +221,7 @@
             goto exit;
         }
 
-        ret =  x509parse_key( &rsa, (unsigned char *) test_srv_key,
+        ret =  x509parse_key( &rsa, (const unsigned char *) test_srv_key,
                               strlen( test_srv_key ), NULL, 0 );
         if( ret != 0 )
         {