diff --git a/tests/testutils.c b/tests/testutils.c
index a215f3f32c59f1eccc1f13b152b88c039eac194e..45882c528860412e7ce6e64770bdf0b8bb5569c1 100644
--- a/tests/testutils.c
+++ b/tests/testutils.c
@@ -717,9 +717,9 @@ int virtTestMain(int argc,
         approxAlloc = virAllocTestCount();
         testCounter++;
         if (virTestGetDebug())
-            fprintf(stderr, "%d) OOM...\n", testCounter);
+            fprintf(stderr, "%zu) OOM...\n", testCounter);
         else
-            fprintf(stderr, "%d) OOM of %d allocs ", testCounter, approxAlloc);
+            fprintf(stderr, "%zu) OOM of %d allocs ", testCounter, approxAlloc);
 
         if (mp) {
             size_t i;