diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 2632574..1a3fd71 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2697,6 +2697,9 @@
                                        psa_key_type_t *key_type,
                                        size_t *key_size)
 {
+#if !defined(MBEDTLS_SSL_HAVE_CCM)
+    (void) taglen;
+#endif
     switch (mbedtls_cipher_type) {
 #if defined(MBEDTLS_SSL_HAVE_AES) && defined(MBEDTLS_SSL_HAVE_CBC)
         case MBEDTLS_CIPHER_AES_128_CBC: