diff --git a/imgui.cpp b/imgui.cpp
index 16110ed65..20983434c 100644
--- a/imgui.cpp
+++ b/imgui.cpp
@@ -332,6 +332,7 @@ ImGuiIO::ImGuiIO()
 
     // User functions
     RenderDrawListsFn = NULL;
+    UserData = NULL;
     MemAllocFn = malloc;
     MemReallocFn = realloc;
     MemFreeFn = free;
diff --git a/imgui.h b/imgui.h
index 576a8693c..4c923280b 100644
--- a/imgui.h
+++ b/imgui.h
@@ -430,6 +430,7 @@ struct ImGuiIO
     // REQUIRED: rendering function. 
     // See example code if you are unsure of how to implement this.
     void        (*RenderDrawListsFn)(ImDrawList** const draw_lists, int count);      
+    void*       UserData;
 
     // Optional: access OS clipboard (default to use native Win32 clipboard on Windows, otherwise use a ImGui private clipboard)
     // Override to access OS clipboard on other architectures.