diff --git a/yesod-test/Yesod/Test.hs b/yesod-test/Yesod/Test.hs
index f2285c0a..eced072c 100644
--- a/yesod-test/Yesod/Test.hs
+++ b/yesod-test/Yesod/Test.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE ImplicitParams #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
 
 {-|
 Yesod.Test is a pragmatic framework for testing web applications built