diff --git a/Library/Homebrew/cask/config.rb b/Library/Homebrew/cask/config.rb
index eba5ecfe0b..404370e689 100644
--- a/Library/Homebrew/cask/config.rb
+++ b/Library/Homebrew/cask/config.rb
@@ -104,9 +104,5 @@ module Cask
         explicit: explicit,
       }.to_json(*args)
     end
-
-    def write(path)
-      path.atomic_write(to_json)
-    end
   end
 end
diff --git a/Library/Homebrew/cask/installer.rb b/Library/Homebrew/cask/installer.rb
index 78c7aa3f4a..88b8e83193 100644
--- a/Library/Homebrew/cask/installer.rb
+++ b/Library/Homebrew/cask/installer.rb
@@ -391,7 +391,7 @@ module Cask
     end
 
     def save_config_file
-      @cask.config.write(@cask.config_path)
+      @cask.config_path.atomic_write(@cask.config.to_json)
     end
 
     def uninstall