diff --git a/Library/Homebrew/dev-cmd/bump-formula-pr.rb b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
index 66a72fe2a4..60c3d387c0 100644
--- a/Library/Homebrew/dev-cmd/bump-formula-pr.rb
+++ b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
@@ -138,7 +138,7 @@ module Homebrew
       [checksum.hash_type, checksum.hexdigest]
     end
 
-    new_hash = @args[hash_type]
+    new_hash = @args[hash_type] if hash_type
     new_tag = @args.tag
     new_revision = @args.revision
     new_mirror = @args.mirror