diff --git a/src/Common/CaresPTRResolver.h b/src/Common/CaresPTRResolver.h
index 0ad1349bb2c..436542f9fd0 100644
--- a/src/Common/CaresPTRResolver.h
+++ b/src/Common/CaresPTRResolver.h
@@ -50,7 +50,7 @@ namespace DB
 
         ares_channel channel;
 
-        [[maybe_unused]] static std::mutex mutex;
+        static std::mutex mutex;
     };
 }