diff --git a/db/plain_table_db_test.cc b/db/plain_table_db_test.cc
index 8a2d85f58..b28abdc1d 100644
--- a/db/plain_table_db_test.cc
+++ b/db/plain_table_db_test.cc
@@ -268,7 +268,7 @@ TEST(PlainTableDBTest, Flush) {
 
       TablePropertiesCollection ptc;
       reinterpret_cast<DB*>(dbfull())->GetPropertiesOfAllTables(&ptc);
-      ASSERT_EQ(1, ptc.size());
+      ASSERT_EQ(1U, ptc.size());
       auto row = ptc.begin();
       auto tp = row->second;
       ASSERT_EQ(