diff --git a/bin/dither/Gemfile.lock b/bin/dither/Gemfile.lock
index e3218db..d9b9454 100644
--- a/bin/dither/Gemfile.lock
+++ b/bin/dither/Gemfile.lock
@@ -5,7 +5,7 @@ GEM
     mini_magick (4.12.0)
     mustermann (3.0.0)
       ruby2_keywords (~> 0.0.1)
-    rack (3.0.9)
+    rack (3.0.9.1)
     rack-protection (4.0.0)
       base64 (>= 0.1.0)
       rack (>= 3.0.0, < 4)