diff --git a/browser/components/migration/FirefoxProfileMigrator.jsm b/browser/components/migration/FirefoxProfileMigrator.jsm
index d333833e69a0..1c26775259e2 100644
--- a/browser/components/migration/FirefoxProfileMigrator.jsm
+++ b/browser/components/migration/FirefoxProfileMigrator.jsm
@@ -71,7 +71,7 @@ FirefoxProfileMigrator.prototype.getResources = function(aProfile) {
   let sourceProfileDir = aProfile ? this._getAllProfiles().get(aProfile.id) :
     Cc["@mozilla.org/toolkit/profile-service;1"]
       .getService(Ci.nsIToolkitProfileService)
-      .currentProfile.rootDir;
+      .defaultProfile.rootDir;
   if (!sourceProfileDir || !sourceProfileDir.exists() ||
       !sourceProfileDir.isReadable())
     return null;
diff --git a/toolkit/profile/nsIProfileMigrator.idl b/toolkit/profile/nsIProfileMigrator.idl
index e2351ca9b438..052b81e07d5c 100644
--- a/toolkit/profile/nsIProfileMigrator.idl
+++ b/toolkit/profile/nsIProfileMigrator.idl
@@ -61,7 +61,7 @@ interface nsIProfileMigrator : nsISupports
    * @note The startup code ignores COM exceptions thrown from this method.
    */
   void migrate(in nsIProfileStartup aStartup, in ACString aKey,
-               [optional] in ACString aProfileName);
+               [optional] in AUTF8String aProfileName);
 };
 
 %{C++