diff --git a/railties/lib/rails/tasks/documentation.rake b/railties/lib/rails/tasks/documentation.rake
index f73e333e83..957c375f6a 100644
--- a/railties/lib/rails/tasks/documentation.rake
+++ b/railties/lib/rails/tasks/documentation.rake
@@ -1,6 +1,6 @@
 namespace :doc do
   def gem_path(gem_name)
-    path = $LOAD_PATH.grep(/#{gem_name}[\w\-\.]*\/lib$/).first
+    path = $LOAD_PATH.grep(/#{gem_name}[\w.-]*\/lib$/).first
     yield File.dirname(path) if path
   end