diff --git a/lib/wayback_machine_downloader.rb b/lib/wayback_machine_downloader.rb
index 1fa5629..84bca6c 100644
--- a/lib/wayback_machine_downloader.rb
+++ b/lib/wayback_machine_downloader.rb
@@ -148,7 +148,7 @@ class WaybackMachineDownloader
         file_path = backup_path + file_path_elements[0..-1].join('/')
       end
       if Gem.win_platform?
-        file_path = file_path.gsub(/[:*?<>\\|]/) {|s| '%' + s.ord.to_s(16) }
+        file_path = file_path.gsub(/[:*?&=<>\\|]/) {|s| '%' + s.ord.to_s(16) }
       end
       unless File.exists? file_path
         begin