diff --git a/gfx/src/gtk/nsDeviceContextGTK.cpp b/gfx/src/gtk/nsDeviceContextGTK.cpp
index 17c32ca4f936..5a36dc54e5ce 100644
--- a/gfx/src/gtk/nsDeviceContextGTK.cpp
+++ b/gfx/src/gtk/nsDeviceContextGTK.cpp
@@ -118,8 +118,6 @@ class nsSystemFontsGTK {
 nscoord nsDeviceContextGTK::mDpi = 96;
 static nsSystemFontsGTK *gSystemFonts = nsnull;
 
-NS_IMPL_ISUPPORTS1(nsDeviceContextGTK, nsIDeviceContext)
-
 nsDeviceContextGTK::nsDeviceContextGTK()
 {
   NS_INIT_REFCNT();
diff --git a/gfx/src/gtk/nsDeviceContextGTK.h b/gfx/src/gtk/nsDeviceContextGTK.h
index c71f1042e24d..be5bec00bd49 100644
--- a/gfx/src/gtk/nsDeviceContextGTK.h
+++ b/gfx/src/gtk/nsDeviceContextGTK.h
@@ -55,8 +55,6 @@ public:
   nsDeviceContextGTK();
   virtual ~nsDeviceContextGTK();
 
-  NS_DECL_ISUPPORTS
-
   static void Shutdown(); // to be called from module destructor
 
   NS_IMETHOD  Init(nsNativeWidget aNativeWidget);