--- a/browser/components/migration/MSMigrationUtils.jsm
+++ b/browser/components/migration/MSMigrationUtils.jsm
@@ -462,18 +462,19 @@ Cookies.prototype = {
     // If UAC is enabled, the most common destination is CookD/Low.  Though,
     // if the user runs the application in administrator mode or disables UAC,
     // cookies are stored in the original CookD destination.  Cause running the
     // browser in administrator mode is unsafe and discouraged, we just care
     // about the UAC state.
     if (!this.__cookiesFolder) {
       let cookiesFolder = Services.dirsvc.get("CookD", Ci.nsIFile);
       if (cookiesFolder.exists() && cookiesFolder.isReadable()) {
-        // Check if UAC is enabled.
-        if (Services.appinfo.QueryInterface(Ci.nsIWinAppHelper).userCanElevate) {
+        // In versions up to Windows 7, check if UAC is enabled.
+        if (AppConstants.isPlatformAndVersionAtMost("win", "6.1") &&
+            Services.appinfo.QueryInterface(Ci.nsIWinAppHelper).userCanElevate) {
           cookiesFolder.append("Low");
         }
         this.__cookiesFolder = cookiesFolder;
       }
     }
     return this.__cookiesFolder;
   },
 
@@ -507,17 +508,17 @@ Cookies.prototype = {
       let success = false;
       let folders = this._migrationType == MSMigrationUtils.MIGRATION_TYPE_EDGE ?
                       this.__cookiesFolders : [this.__cookiesFolder];
       for (let folder of folders) {
         let entries = folder.directoryEntries;
         while (entries.hasMoreElements()) {
           let entry = entries.getNext().QueryInterface(Ci.nsIFile);
           // Skip eventual bogus entries.
-          if (!entry.isFile() || !/\.txt$/.test(entry.leafName))
+          if (!entry.isFile() || !/\.(cookie|txt)$/.test(entry.leafName))
             continue;
 
           this._readCookieFile(entry, function(aSuccess) {
             // Importing even a single cookie file is considered a success.
             if (aSuccess)
               success = true;
             try {
               cookiesGenerator.next();