diff --git a/imgui.h b/imgui.h
index d7d62fe6..cc4e4a9a 100644
--- a/imgui.h
+++ b/imgui.h
@@ -351,7 +351,7 @@ namespace ImGui
     IMGUI_API bool          TreeNodeEx(const void* ptr_id, ImGuiTreeNodeFlags flags, const char* fmt, ...) IM_FMTARGS(3);
     IMGUI_API bool          TreeNodeExV(const char* str_id, ImGuiTreeNodeFlags flags, const char* fmt, va_list args) IM_FMTLIST(3);
     IMGUI_API bool          TreeNodeExV(const void* ptr_id, ImGuiTreeNodeFlags flags, const char* fmt, va_list args) IM_FMTLIST(3);
-    IMGUI_API void          TreePush(const char* str_id = NULL);                                    // ~ Indent()+PushId(). Already called by TreeNode() when returning true, but you can call Push/Pop yourself for layout purpose
+    IMGUI_API void          TreePush(const char* str_id);                                           // ~ Indent()+PushId(). Already called by TreeNode() when returning true, but you can call Push/Pop yourself for layout purpose
     IMGUI_API void          TreePush(const void* ptr_id = NULL);                                    // "
     IMGUI_API void          TreePop();                                                              // ~ Unindent()+PopId()
     IMGUI_API void          TreeAdvanceToLabelPos();                                                // advance cursor x position by GetTreeNodeToLabelSpacing()