diff --git a/lib/clockwork_web.rb b/lib/clockwork_web.rb
index 1c0809c..9d474fa 100644
--- a/lib/clockwork_web.rb
+++ b/lib/clockwork_web.rb
@@ -3,7 +3,7 @@
 require "safely/core"
 
 # modules
-require_relative "clockwork_web/engine"
+require_relative "clockwork_web/engine" if defined?(Rails)
 require_relative "clockwork_web/version"
 
 module ClockworkWeb