diff --git a/mozilla/content/html/style/src/nsCSSRules.h b/mozilla/content/html/style/src/nsCSSRules.h
index 353f0e70c2b..c9cdced88cc 100644
--- a/mozilla/content/html/style/src/nsCSSRules.h
+++ b/mozilla/content/html/style/src/nsCSSRules.h
@@ -73,7 +73,7 @@ protected:
 
   // to help implement nsIStyleRule
 #ifdef DEBUG
-  nsresult List(FILE* out = stdout, PRInt32 aIndent = 0) const;
+  NS_IMETHOD List(FILE* out = stdout, PRInt32 aIndent = 0) const;
 #endif
 
 public:
diff --git a/mozilla/layout/style/nsCSSRules.h b/mozilla/layout/style/nsCSSRules.h
index 353f0e70c2b..c9cdced88cc 100644
--- a/mozilla/layout/style/nsCSSRules.h
+++ b/mozilla/layout/style/nsCSSRules.h
@@ -73,7 +73,7 @@ protected:
 
   // to help implement nsIStyleRule
 #ifdef DEBUG
-  nsresult List(FILE* out = stdout, PRInt32 aIndent = 0) const;
+  NS_IMETHOD List(FILE* out = stdout, PRInt32 aIndent = 0) const;
 #endif
 
 public: