diff --git a/lcl/interfaces/gtk/gtkwsbuttons.pp b/lcl/interfaces/gtk/gtkwsbuttons.pp
index 8392a41938..40e12184bb 100644
--- a/lcl/interfaces/gtk/gtkwsbuttons.pp
+++ b/lcl/interfaces/gtk/gtkwsbuttons.pp
@@ -38,7 +38,7 @@ uses
   // widgetset
   WSButtons, WSProc,
   // interface
-  GtkDef;
+  GtkDef, GtkExtra;
 
 type
   PBitBtnWidgetInfo = ^TBitBtnWidgetInfo;