diff --git a/paddle/fluid/framework/no_need_buffer_vars_inference.h b/paddle/fluid/framework/no_need_buffer_vars_inference.h
index 9124489ec686e5ac0744cbdc3f8d04a5770815b9..c1640f6ccb8eed31096dfe9b8c66ecf7636d75b1 100644
--- a/paddle/fluid/framework/no_need_buffer_vars_inference.h
+++ b/paddle/fluid/framework/no_need_buffer_vars_inference.h
@@ -114,7 +114,7 @@ class InferNoNeedBufferVarsFN {
     return (*inferer_)(ctx);
   }
 
-  inline operator bool() const { return inferer_ != nullptr; }
+  inline explicit operator bool() const { return inferer_ != nullptr; }
 
   inline bool operator!() const { return inferer_ == nullptr; }