diff --git a/lib/uh/wm.rb b/lib/uh/wm.rb
index 6e95692..6b6098a 100644
--- a/lib/uh/wm.rb
+++ b/lib/uh/wm.rb
@@ -1,5 +1,6 @@
 require 'forwardable'
 require 'logger'
+require 'optparse'
 require 'uh'
 
 require 'uh/wm/cli'