diff --git a/application/test/application_main_document_browsertest.cc b/application/test/application_main_document_browsertest.cc
index 1fd5f4f9de..28e8ec22c9 100644
--- a/application/test/application_main_document_browsertest.cc
+++ b/application/test/application_main_document_browsertest.cc
@@ -61,7 +61,7 @@ IN_PROC_BROWSER_TEST_F(ApplicationMainDocumentBrowserTest, MainDocument) {
   content::RunAllPendingInMessageLoop();
   const xwalk::RuntimeList& runtimes = RuntimeRegistry::Get()->runtimes();
   // At least the main document's runtime exist after launch.
-  ASSERT_GE(runtimes.size(), 1);
+  ASSERT_GE(runtimes.size(), 1U);
 
   Runtime* main_runtime = runtimes[0];
   xwalk::RuntimeContext* runtime_context = main_runtime->runtime_context();