diff --git a/tests/libtest/first.c b/tests/libtest/first.c
index a195a9815a..37f4e85fdd 100644
--- a/tests/libtest/first.c
+++ b/tests/libtest/first.c
@@ -163,7 +163,7 @@ CURLcode ws_send_ping(CURL *curl, const char *send_payload)
   size_t sent;
   CURLcode result = curl_ws_send(curl, send_payload, strlen(send_payload),
                                  &sent, 0, CURLWS_PING);
-  curl_mfprintf(stderr, "ws: curl_ws_send returned %u, sent %zu\n",
+  curl_mfprintf(stderr, "ws: curl_ws_send returned %d, sent %zu\n",
                 result, sent);
   return result;
 }
@@ -175,7 +175,7 @@ CURLcode ws_recv_pong(CURL *curl, const char *expected_payload)
   char buffer[256];
   CURLcode result = curl_ws_recv(curl, buffer, sizeof(buffer), &rlen, &meta);
   if(result) {
-    curl_mfprintf(stderr, "ws: curl_ws_recv returned %u, received %zu\n",
+    curl_mfprintf(stderr, "ws: curl_ws_recv returned %d, received %zu\n",
                   result, rlen);
     return result;
   }