diff --git a/openmp/runtime/test/omp_testsuite.h b/openmp/runtime/test/omp_testsuite.h
--- a/openmp/runtime/test/omp_testsuite.h
+++ b/openmp/runtime/test/omp_testsuite.h
@@ -104,7 +104,8 @@
   info->arg = arg;
   pthread = CreateThread(NULL, 0, __thread_func_wrapper, info, 0, NULL);
   if (pthread == NULL) {
-    fprintf(stderr, "CreateThread() failed: Error #%u.\n", GetLastError());
+    fprintf(stderr, "CreateThread() failed: Error #%u.\n",
+            (unsigned) GetLastError());
     exit(1);
   }
   *thread = pthread;
@@ -116,12 +117,13 @@
   rc = WaitForSingleObject(thread, INFINITE);
   if (rc == WAIT_FAILED) {
     fprintf(stderr, "WaitForSingleObject() failed: Error #%u.\n",
-            GetLastError());
+            (unsigned) GetLastError());
     exit(1);
   }
   rc = CloseHandle(thread);
   if (rc == 0) {
-    fprintf(stderr, "CloseHandle() failed: Error #%u.\n", GetLastError());
+    fprintf(stderr, "CloseHandle() failed: Error #%u.\n",
+            (unsigned) GetLastError());
     exit(1);
   }
   return 0;