diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 072f626..b0fb5a8 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3967,6 +3967,9 @@
             break;
 #endif /* MBEDTLS_ECDH_C */
         default:
+            (void) private_key;
+            (void) peer_key;
+            (void) peer_key_length;
             return( PSA_ERROR_NOT_SUPPORTED );
     }
     if( status != PSA_SUCCESS )