diff --git a/app/models/repository/mercurial.rb b/app/models/repository/mercurial.rb
index 4c6fae23d..60948ce55 100644
--- a/app/models/repository/mercurial.rb
+++ b/app/models/repository/mercurial.rb
@@ -115,7 +115,7 @@ class Repository::Mercurial < Repository
                  AND (#{Change.table_name}.path = ?
                        OR #{Change.table_name}.path LIKE ? ESCAPE ?))"
       args << path.with_leading_slash
-      args << "#{path.with_leading_slash.gsub(/[%_\\]/) { |s| "\\#{s}" }}/%" << '\\'
+      args << "#{path.with_leading_slash.gsub(%r{[%_\\]}) { |s| "\\#{s}" }}/%" << '\\'
     end
 
     [cond.join(' AND '), *args] unless cond.empty?