diff --git a/netwerk/base/src/nsPACMan.cpp b/netwerk/base/src/nsPACMan.cpp
index 93a1865a236..f3313d03c85 100644
--- a/netwerk/base/src/nsPACMan.cpp
+++ b/netwerk/base/src/nsPACMan.cpp
@@ -369,6 +369,7 @@ nsPACMan::LoadPACFromURI(const nsCString &spec)
   if (!spec.IsEmpty()) {
     mPACURISpec = spec;
     mPACURIRedirectSpec.Truncate();
+    mNormalPACURISpec.Truncate(); // set at load time
     mLoadFailureCount = 0;  // reset
   }
 
@@ -399,6 +400,7 @@ nsPACMan::StartLoading()
 
       // NOTE: This results in GetProxyForURI being called
       if (pacURI) {
+        pacURI->GetSpec(mNormalPACURISpec);
         ios->NewChannelFromURI(pacURI, getter_AddRefs(channel));
       }
       else {
diff --git a/netwerk/base/src/nsPACMan.h b/netwerk/base/src/nsPACMan.h
index 55d02501f7b..7d092829308 100644
--- a/netwerk/base/src/nsPACMan.h
+++ b/netwerk/base/src/nsPACMan.h
@@ -136,7 +136,8 @@ public:
    */
   bool IsPACURI(const nsACString &spec)
   {
-    return mPACURISpec.Equals(spec) || mPACURIRedirectSpec.Equals(spec);
+    return mPACURISpec.Equals(spec) || mPACURIRedirectSpec.Equals(spec) ||
+      mNormalPACURISpec.Equals(spec);
   }
 
   bool IsPACURI(nsIURI *uri) {
@@ -206,8 +207,13 @@ private:
 
   mozilla::LinkedList<PendingPACQuery> mPendingQ; /* pac thread only */
 
-  nsCString                    mPACURISpec; // Not an nsIURI for use off main thread
+  // These specs are not nsIURI so that they can be used off the main thread.
+  // The non-normalized versions are directly from the configuration, the
+  // normalized version has been extracted from an nsIURI
+  nsCString                    mPACURISpec;
   nsCString                    mPACURIRedirectSpec;
+  nsCString                    mNormalPACURISpec;
+
   nsCOMPtr<nsIStreamLoader>    mLoader;
   bool                         mLoadPending;
   bool                         mShutdown;