diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 4a0bd83..e45b5d7 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3592,6 +3592,7 @@
             break;
 #endif /* PSA_WANT_ALG_CHACHA20_POLY1305 */
         default:
+            (void) nonce_length;
             return( PSA_ERROR_NOT_SUPPORTED );
     }