diff --git a/chrome/src/nsChromeRegistry.h b/chrome/src/nsChromeRegistry.h
index 3f82b2367c8..81b246899b7 100644
--- a/chrome/src/nsChromeRegistry.h
+++ b/chrome/src/nsChromeRegistry.h
@@ -116,7 +116,7 @@ protected:
 
   // Update the selected locale used by the chrome registry, and fire a
   // notification about this change
-  virtual void UpdateSelectedLocale() = 0;
+  virtual nsresult UpdateSelectedLocale() = 0;
 
   static void LogMessage(const char* aMsg, ...);
   static void LogMessageWithContext(nsIURI* aURL, PRUint32 aLineNumber, PRUint32 flags,
diff --git a/chrome/src/nsChromeRegistryChrome.cpp b/chrome/src/nsChromeRegistryChrome.cpp
index 3ca506ba999..c223a36227e 100644
--- a/chrome/src/nsChromeRegistryChrome.cpp
+++ b/chrome/src/nsChromeRegistryChrome.cpp
@@ -368,12 +368,9 @@ nsChromeRegistryChrome::Observe(nsISupports *aSubject, const char *aTopic,
 
     if (pref.EqualsLiteral(MATCH_OS_LOCALE_PREF) ||
         pref.EqualsLiteral(SELECTED_LOCALE_PREF)) {
-      if (!mProfileLoaded) {
-        rv = SelectLocaleFromPref(prefs);
-        if (NS_FAILED(rv))
-          return rv;
-      }
-      FlushAllCaches();
+        rv = UpdateSelectedLocale();
+        if (NS_SUCCEEDED(rv) && mProfileLoaded)
+          FlushAllCaches();
     }
     else if (pref.EqualsLiteral(SELECTED_SKIN_PREF)) {
       nsXPIDLCString provider;
@@ -426,11 +423,12 @@ nsChromeRegistryChrome::CheckForNewChrome()
   return NS_OK;
 }
 
-void nsChromeRegistryChrome::UpdateSelectedLocale()
+nsresult nsChromeRegistryChrome::UpdateSelectedLocale()
 {
+  nsresult rv = NS_OK;
   nsCOMPtr<nsIPrefBranch> prefs(do_GetService(NS_PREFSERVICE_CONTRACTID));
   if (prefs) {
-    nsresult rv = SelectLocaleFromPref(prefs);
+    rv = SelectLocaleFromPref(prefs);
     if (NS_SUCCEEDED(rv)) {
       nsCOMPtr<nsIObserverService> obsSvc =
         mozilla::services::GetObserverService();
@@ -439,6 +437,8 @@ void nsChromeRegistryChrome::UpdateSelectedLocale()
                               "selected-locale-has-changed", nsnull);
     }
   }
+
+  return rv;
 }
 
 static void
diff --git a/chrome/src/nsChromeRegistryChrome.h b/chrome/src/nsChromeRegistryChrome.h
index 44bd07c7f0a..8bd6cedfecb 100644
--- a/chrome/src/nsChromeRegistryChrome.h
+++ b/chrome/src/nsChromeRegistryChrome.h
@@ -83,7 +83,7 @@ class nsChromeRegistryChrome : public nsChromeRegistry
                                          PRUint32 number, void *arg);
 
   nsresult SelectLocaleFromPref(nsIPrefBranch* prefs);
-  NS_OVERRIDE void UpdateSelectedLocale();
+  NS_OVERRIDE nsresult UpdateSelectedLocale();
   NS_OVERRIDE nsIURI* GetBaseURIFromPackage(const nsCString& aPackage,
                                              const nsCString& aProvider,
                                              const nsCString& aPath);
diff --git a/chrome/src/nsChromeRegistryContent.cpp b/chrome/src/nsChromeRegistryContent.cpp
index d5982833e9f..cc7c11885f3 100644
--- a/chrome/src/nsChromeRegistryContent.cpp
+++ b/chrome/src/nsChromeRegistryContent.cpp
@@ -278,9 +278,9 @@ nsChromeRegistryContent::GetXULOverlays(nsIURI *aChromeURL,
   CONTENT_NOT_IMPLEMENTED();
 }
 
-void nsChromeRegistryContent::UpdateSelectedLocale()
+nsresult nsChromeRegistryContent::UpdateSelectedLocale()
 {
-  CONTENT_NOTREACHED();
+  CONTENT_NOT_IMPLEMENTED();
 }
 
 void
diff --git a/chrome/src/nsChromeRegistryContent.h b/chrome/src/nsChromeRegistryContent.h
index 06421aa562b..09f81735d0b 100644
--- a/chrome/src/nsChromeRegistryContent.h
+++ b/chrome/src/nsChromeRegistryContent.h
@@ -89,7 +89,7 @@ class nsChromeRegistryContent : public nsChromeRegistry
   void RegisterResource(const ResourceMapping& aResource);
   void RegisterOverride(const OverrideMapping& aOverride);
 
-  NS_OVERRIDE void UpdateSelectedLocale();
+  NS_OVERRIDE nsresult UpdateSelectedLocale();
   NS_OVERRIDE nsIURI* GetBaseURIFromPackage(const nsCString& aPackage,
                                  const nsCString& aProvider,
                                  const nsCString& aPath);