diff --git a/accessible/src/base/nsAccessible.h b/accessible/src/base/nsAccessible.h
index 578e511223ef..3f36ba7e327f 100644
--- a/accessible/src/base/nsAccessible.h
+++ b/accessible/src/base/nsAccessible.h
@@ -123,7 +123,7 @@ public:
    * second argument is omitted then second bit field of accessible state won't
    * be calculated.
    */
-  nsresult GetState(PRUint32 *aState, PRUint32 *aExtraState);
+  NS_IMETHOD GetState(PRUint32 *aState, PRUint32 *aExtraState);
 
   /**
    * Returns attributes for accessible without explicitly setted ARIA