diff --git a/lib/active_support/cache/mongo_store.rb b/lib/active_support/cache/mongo_store.rb
index 82eb7f6..76bf577 100644
--- a/lib/active_support/cache/mongo_store.rb
+++ b/lib/active_support/cache/mongo_store.rb
@@ -97,7 +97,7 @@ def delete_matched(pattern, options=nil)
     end
     
     module Store
-      rails3 = defined?(::Rails) && ::Rails.version =~ /^3\./
+      rails3 = defined?(::Rails) && ::Rails.version =~ /^(3|4)\./
       include rails3 ? Rails3 : Rails2
       
       def expires_in
@@ -191,4 +191,4 @@ def make_collection
         
     end
   end
-end
\ No newline at end of file
+end