diff --git a/modules/libpr0n/src/imgLoader.cpp b/modules/libpr0n/src/imgLoader.cpp
index 17d79866b092..8deddb1e4be6 100644
--- a/modules/libpr0n/src/imgLoader.cpp
+++ b/modules/libpr0n/src/imgLoader.cpp
@@ -1815,8 +1815,8 @@ NS_IMETHODIMP imgLoader::LoadImageWithChannel(nsIChannel *channel, imgIDecoderOb
   nsCOMPtr<nsILoadGroup> loadGroup;
   channel->GetLoadGroup(getter_AddRefs(loadGroup));
 
-  // XXX: It looks like the wrong load flags are being passed in...
-  requestFlags &= 0xFFFF;
+  // Filter out any load flags not from nsIRequest
+  requestFlags &= nsIRequest::LOAD_REQUESTMASK;
 
   nsresult rv = NS_OK;
   if (request) {
diff --git a/netwerk/base/public/nsIRequest.idl b/netwerk/base/public/nsIRequest.idl
index a7f114b38e57..76c4a585544b 100644
--- a/netwerk/base/public/nsIRequest.idl
+++ b/netwerk/base/public/nsIRequest.idl
@@ -135,6 +135,11 @@ interface nsIRequest : nsISupports
      */
     attribute nsLoadFlags loadFlags;
 
+    /**
+     * Mask defining the bits reserved for nsIRequest LoadFlags
+     */
+    const unsigned long LOAD_REQUESTMASK = 0xFFFF;
+
     /**************************************************************************
      * Listed below are the various load flags which may be or'd together.
      */
diff --git a/netwerk/base/src/nsLoadGroup.cpp b/netwerk/base/src/nsLoadGroup.cpp
index 643a64dab12d..11463197858b 100644
--- a/netwerk/base/src/nsLoadGroup.cpp
+++ b/netwerk/base/src/nsLoadGroup.cpp
@@ -506,7 +506,7 @@ nsLoadGroup::SetDefaultLoadRequest(nsIRequest *aRequest)
         // Mask off any bits that are not part of the nsIRequest flags.
         // in particular, nsIChannel::LOAD_DOCUMENT_URI...
         //
-        mLoadFlags &= 0xFFFF;
+        mLoadFlags &= nsIRequest::LOAD_REQUESTMASK;
     }
     // Else, do not change the group's load flags (see bug 95981)
     return NS_OK;