diff --git a/src/coap_notls.c b/src/coap_notls.c
index e1c86643..621ab0f4 100644
--- a/src/coap_notls.c
+++ b/src/coap_notls.c
@@ -50,7 +50,7 @@ int coap_dtls_context_set_psk(coap_context_t *ctx UNUSED,
   return 0;
 }
 
-int coap_dtls_context_check_keys_enabled(coap_context_t *ctx)
+int coap_dtls_context_check_keys_enabled(coap_context_t *ctx UNUSED)
 {
   return 0;
 }