diff --git a/panda/src/device/clientButtonDevice.h b/panda/src/device/clientButtonDevice.h
index df7bbde363..da8e576483 100644
--- a/panda/src/device/clientButtonDevice.h
+++ b/panda/src/device/clientButtonDevice.h
@@ -85,6 +85,7 @@ public:
  
 private:
   static TypeHandle _type_handle;
+  friend class ButtonState;
 };
 
 #include "clientButtonDevice.I"