diff --git a/Library/Homebrew/tap.rb b/Library/Homebrew/tap.rb
index 74b9014f6f..d8605c280a 100644
--- a/Library/Homebrew/tap.rb
+++ b/Library/Homebrew/tap.rb
@@ -1116,7 +1116,7 @@ class Tap
       return false unless list.include? formula_or_cask
       return list[formula_or_cask] if value.blank?
 
-      return list[formula_or_cask].include? value if list[formula_or_cask].is_a? Array
+      return list[formula_or_cask].include?(value) if list[formula_or_cask].is_a?(Array)
 
       list[formula_or_cask] == value
     end