diff --git a/programs/ssl/ssl_client2.c b/programs/ssl/ssl_client2.c
index f4cbe00..214733b 100644
--- a/programs/ssl/ssl_client2.c
+++ b/programs/ssl/ssl_client2.c
@@ -65,16 +65,16 @@
  */
 struct options
 {
-    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 debug_level;            /* level of debugging                       */
-    char *request_page;         /* page on server to request                */
-    char *ca_file;              /* the file with the CA certificate(s)      */
-    char *ca_path;              /* the path with the CA certificate(s) reside */
-    char *crt_file;             /* the file with the client certificate     */
-    char *key_file;             /* the file with the client key             */
-    char *psk;                  /* the pre-shared key                       */
-    char *psk_identity;         /* the pre-shared key identity              */
+    const char *request_page;   /* page on server to request                */
+    const char *ca_file;        /* the file with the CA certificate(s)      */
+    const char *ca_path;        /* the path with the CA certificate(s) reside */
+    const char *crt_file;       /* the file with the client certificate     */
+    const char *key_file;       /* the file with the client key             */
+    const char *psk;            /* the pre-shared key                       */
+    const char *psk_identity;   /* the pre-shared key identity              */
     int force_ciphersuite[2];   /* protocol/ciphersuite to use, or all      */
     int renegotiation;          /* enable / disable renegotiation           */
     int allow_legacy;           /* allow legacy renegotiation               */
@@ -203,7 +203,7 @@
     unsigned char psk[256];
     size_t psk_len = 0;
 #endif
-    char *pers = "ssl_client2";
+    const char *pers = "ssl_client2";
 
     entropy_context entropy;
     ctr_drbg_context ctr_drbg;
@@ -449,7 +449,8 @@
 
     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( " failed\n  ! ctr_drbg_init returned -0x%x\n", -ret );
         goto exit;
@@ -472,7 +473,7 @@
     else
 #endif
 #if defined(POLARSSL_CERTS_C)
-        ret = x509parse_crt( &cacert, (unsigned char *) test_ca_crt,
+        ret = x509parse_crt( &cacert, (const unsigned char *) test_ca_crt,
                 strlen( test_ca_crt ) );
 #else
     {
@@ -502,7 +503,7 @@
     else
 #endif
 #if defined(POLARSSL_CERTS_C)
-        ret = x509parse_crt( &clicert, (unsigned char *) test_cli_crt,
+        ret = x509parse_crt( &clicert, (const unsigned char *) test_cli_crt,
                 strlen( test_cli_crt ) );
 #else
     {
@@ -522,7 +523,7 @@
     else
 #endif
 #if defined(POLARSSL_CERTS_C)
-        ret = x509parse_key( &rsa, (unsigned char *) test_cli_key,
+        ret = x509parse_key( &rsa, (const unsigned char *) test_cli_key,
                 strlen( test_cli_key ), NULL, 0 );
 #else
     {