diff --git a/lsplant/src/main/jni/art/mirror/class.hpp b/lsplant/src/main/jni/art/mirror/class.hpp
index 90ac070..09d1f0c 100644
--- a/lsplant/src/main/jni/art/mirror/class.hpp
+++ b/lsplant/src/main/jni/art/mirror/class.hpp
@@ -62,7 +62,7 @@ private:
                 }
             }
         }
-        {
+        if (!out.empty()) [[unlikely]] {
             std::unique_lock lk(backup_methods_lock_);
             backup_methods_[self].emplace(class_def, std::move(out));
         }