diff --git a/Library/Contributions/cmds/brew-mirror-check.rb b/Library/Contributions/cmds/brew-mirror-check.rb
index 1ae06ce6aa..0f398c171c 100755
--- a/Library/Contributions/cmds/brew-mirror-check.rb
+++ b/Library/Contributions/cmds/brew-mirror-check.rb
@@ -2,8 +2,10 @@ require 'formula'
 
 class Formula
   def test_mirror mirror
-    url, specs = mirror.values_at :url, :specs
-    downloader = download_strategy.new url, name, version, specs
+    # Checksum verification is done against @active_spec, so we need only
+    # populate the stub spec object with the mirror URL.
+    spec = SoftwareSpec.new(mirror)
+    downloader = download_strategy.new(name, spec)
 
     # Force the downloader to attempt the download by removing the tarball if
     # it is allready cached.