diff --git a/tool/sync_default_gems.rb b/tool/sync_default_gems.rb
index 1a8f54b306..7c894222ae 100644
--- a/tool/sync_default_gems.rb
+++ b/tool/sync_default_gems.rb
@@ -326,7 +326,7 @@ def sync_default_gems(gem)
   end
 end
 
-IGNORE_FILE_PATTERN = /\A(?:\.travis.yml|appveyor\.yml|azure\-pipelines\.yml|\.git(?:ignore|hub)|Gemfile|README\.md|History\.txt|Rakefile|CODE_OF_CONDUCT\.md)/
+IGNORE_FILE_PATTERN = /\A(?:\.travis.yml|appveyor\.yml|azure-pipelines\.yml|\.git(?:ignore|hub)|Gemfile|README\.md|History\.txt|Rakefile|CODE_OF_CONDUCT\.md)/
 
 def sync_default_gems_with_commits(gem, range)
   puts "Sync #{$repositories[gem.to_sym]} with commit history."