diff --git a/paddle/fluid/imperative/layer.cc b/paddle/fluid/imperative/layer.cc
index aaafb4e87f4d44391f6be45263ddd80898e2c385..c0a337a2b5a497e4e65375ff1b6f7f26b73f460d 100644
--- a/paddle/fluid/imperative/layer.cc
+++ b/paddle/fluid/imperative/layer.cc
@@ -27,6 +27,9 @@
 namespace paddle {
 namespace imperative {
 
+const char* PyLayer::kFwdInp = PyLayer::kFwdInp;
+const char* PyLayer::kFwdOut = PyLayer::kFwdOut;
+
 std::map<int, py::object> py_funcs_;
 
 using framework::Variable;
diff --git a/paddle/fluid/imperative/layer.h b/paddle/fluid/imperative/layer.h
index 14d89ca40edae2a932dfbf0f0b796e0e9e1994a5..34aa701c5b9ec432843c5ce995afaf20e30e4829 100644
--- a/paddle/fluid/imperative/layer.h
+++ b/paddle/fluid/imperative/layer.h
@@ -200,8 +200,8 @@ class PyLayer {
  public:
   virtual ~PyLayer() {}
 
-  static constexpr char* kFwdInp = "X";
-  static constexpr char* kFwdOut = "Out";
+  static const char* kFwdInp;
+  static const char* kFwdOut;
 
   static void RegisterFunc(int func_id, const py::object& py_func);