--- a/widget/moz.build
+++ b/widget/moz.build
@@ -137,17 +137,16 @@ UNIFIED_SOURCES += [
     'CompositorWidgetProxy.cpp',
     'ContentCache.cpp',
     'GfxDriverInfo.cpp',
     'GfxInfoBase.cpp',
     'GfxInfoCollector.cpp',
     'GfxInfoWebGL.cpp',
     'InputData.cpp',
     'nsBaseAppShell.cpp',
-    'nsBaseDragService.cpp',
     'nsBaseScreen.cpp',
     'nsClipboardHelper.cpp',
     'nsClipboardProxy.cpp',
     'nsColorPickerProxy.cpp',
     'nsContentProcessWidgetFactory.cpp',
     'nsDragServiceProxy.cpp',
     'nsFilePickerProxy.cpp',
     'nsHTMLFormatConverter.cpp',
@@ -178,16 +177,17 @@ if CONFIG['MOZ_XUL'] and CONFIG['NS_PRIN
         'nsDeviceContextSpecProxy.cpp',
         'nsPrintOptionsImpl.cpp',
         'nsPrintSession.cpp',
     ]
 
 # nsBaseWidget.cpp needs to be built separately because of name clashes in the OS X headers
 SOURCES += [
     'nsBaseWidget.cpp',
+    'nsBaseDragService.cpp'
 ]
 
 if CONFIG['MOZ_INSTRUMENT_EVENT_LOOP']:
     EXPORTS.mozilla += [
         'WidgetTraceEvent.h',
     ]
 
 EXPORTS.ipc = ['nsGUIEventIPC.h']