diff --git a/lib/cf-ip-happy.c b/lib/cf-ip-happy.c
index f63de79486..c41a7442db 100644
--- a/lib/cf-ip-happy.c
+++ b/lib/cf-ip-happy.c
@@ -403,7 +403,7 @@ evaluate:
   }
   if(bs->running)
     CURL_TRC_CF(data, cf, "checked connect attempts: "
-                "%d ongoing, %d inconclusive", ongoing, inconclusive);
+                "%u ongoing, %u inconclusive", ongoing, inconclusive);
 
   /* no attempt connected yet, start another one? */
   if(!ongoing) {