diff --git a/Library/Homebrew/dev-cmd/contributions.rb b/Library/Homebrew/dev-cmd/contributions.rb
index ead3abd767..de13dbe777 100755
--- a/Library/Homebrew/dev-cmd/contributions.rb
+++ b/Library/Homebrew/dev-cmd/contributions.rb
@@ -38,7 +38,7 @@ module Homebrew
     end
   end
 
-  sig { returns(NilClass) }
+  sig { void }
   def contributions
     args = contributions_args.parse