diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index 0447345d6a1d..38915d021c27 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -124,11 +124,12 @@ static int ssl_write_early_data_postprocess( mbedtls_ssl_context* ssl );
 int ssl_write_early_data_process( mbedtls_ssl_context* ssl )
 {
     int ret;
-#if defined(MBEDTLS_SSL_USE_MPS)
+#if defined(MBEDTLS_SSL_USE_MPS) & defined(MBEDTLS_ZERO_RTT)
     mbedtls_writer *msg;
     unsigned char *buf;
     mbedtls_mps_size_t buf_len, msg_len;
-#endif /* MBEDTLS_SSL_USE_MPS */
+#endif /* MBEDTLS_SSL_USE_MPS & MBEDTLS_ZERO_RTT */
+    
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write early data" ) );
 
     MBEDTLS_SSL_PROC_CHK_NEG( ssl_write_early_data_coordinate( ssl ) );
@@ -176,10 +177,7 @@ int ssl_write_early_data_process( mbedtls_ssl_context* ssl )
 #endif /* MBEDTLS_SSL_USE_MPS */
 
 #else /* MBEDTLS_ZERO_RTT */
-        ((void) buf);
-        ((void) buf_len);
-        ((void) msg);
-        ((void) msg_len);
+      
         /* Should never happen */
         return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
 
@@ -2725,6 +2723,11 @@ static int ssl_encrypted_extensions_parse( mbedtls_ssl_context* ssl,
     size_t ext_len;
     const unsigned char *ext;
 
+#if !( defined(MBEDTLS_SSL_ALPN) || defined(MBEDTLS_ZERO_RTT) || \
+       defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) )
+    ((void) ssl);
+#endif /* ! (MBEDTLS_SSL_ALPN || MBEDTLS_ZERO_RTT || MBEDTLS_SSL_MAX_FRAGMENT_LENGTH) */
+    
     if( buflen < 2 )
     {
         MBEDTLS_SSL_DEBUG_MSG( 1, ( "EncryptedExtension message too short" ) );
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 3804526f9494..b6d0c0db76bb 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -871,9 +871,12 @@ int mbedtls_ssl_tls1_3_generate_resumption_master_secret(
     int ret = 0;
 
     mbedtls_md_type_t md_type;
+    
+#if defined(MBEDTLS_DEBUG_C)  
     mbedtls_md_info_t const *md_info;
     size_t md_size;
-
+#endif /* MBEDTLS_DEBUG_C */
+    
     unsigned char transcript[MBEDTLS_MD_MAX_SIZE];
     size_t transcript_len;
 
@@ -881,9 +884,11 @@ int mbedtls_ssl_tls1_3_generate_resumption_master_secret(
           ( "=> mbedtls_ssl_tls1_3_generate_resumption_master_secret" ) );
 
     md_type = ssl->handshake->ciphersuite_info->mac;
+#if defined(MBEDTLS_DEBUG_C)
     md_info = mbedtls_md_info_from_type( md_type );
     md_size = mbedtls_md_get_size( md_info );
-
+#endif /* MBEDTLS_DEBUG_C */
+    
     ret = mbedtls_ssl_get_handshake_transcript( ssl, md_type,
                                                 transcript, sizeof( transcript ),
                                                 &transcript_len );
@@ -1153,6 +1158,11 @@ int mbedtls_ssl_tls1_3_create_psk_binder( mbedtls_ssl_context *ssl,
     mbedtls_md_info_t const *md_info = mbedtls_md_info_from_type( md_type );
     size_t const md_size = mbedtls_md_get_size( md_info );
 
+#if !defined(MBEDTLS_DEBUG_C)
+    ssl = NULL;
+    ((void) ssl);
+#endif /* MBEDTLS_DEBUG_C */
+    
     ret = mbedtls_ssl_tls1_3_evolve_secret( md_type,
                                             NULL,          /* Old secret */
                                             psk, psk_len,  /* Input      */
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 3bd8566152c9..63870394cb46 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -2267,6 +2267,12 @@ static int ssl_client_hello_fetch( mbedtls_ssl_context* ssl,
 
 #endif /* MBEDTLS_SSL_USE_MPS */
 
+#if !defined(MBEDTLS_DEBUG_C)
+static void ssl_debug_print_client_hello_exts( mbedtls_ssl_context *ssl )
+{
+    ((void) ssl);
+}
+#else
 static void ssl_debug_print_client_hello_exts( mbedtls_ssl_context *ssl )
 {
     MBEDTLS_SSL_DEBUG_MSG( 3, ( "Supported Extensions:" ) );
@@ -2314,6 +2320,7 @@ static void ssl_debug_print_client_hello_exts( mbedtls_ssl_context *ssl )
                                 "TRUE" : "FALSE" ) );
 #endif /* MBEDTLS_ZERO_RTT*/
 }
+#endif /* !MBEDTLS_DEBUG_C */
 
 static int ssl_client_hello_has_psk_extensions( mbedtls_ssl_context *ssl )
 {