diff --git a/modules/libimg/public/ilINetReader.h b/modules/libimg/public/ilINetReader.h
index 6ed65f21c14..f1b55f8ddd8 100644
--- a/modules/libimg/public/ilINetReader.h
+++ b/modules/libimg/public/ilINetReader.h
@@ -34,7 +34,7 @@ class ilIURL;
 class ilINetReader : public nsISupports {
 public:
 
-  virtual unsigned int WriteReady()=0;
+  /*NS_IMETHOD*/virtual int WriteReady()=0;
   
   virtual int FirstWrite(const unsigned char *str, int32 len)=0;