diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 7f7e4e03e5..f3cc3eb8a4 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -2236,7 +2236,10 @@ class Formula
       if args.nil?
         @licenses
       else
-        args = { any_of: args } if args.is_a? Array
+        if args.is_a? Array
+          odeprecated "`license [...]`", "`license any_of: [...]`"
+          args = { any_of: args }
+        end
         @licenses = args
       end
     end