diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # ChangeLog for yesod-core
 
+## 1.6.18.8
+
+* Fix test suite for wai-extra change around vary header
+
 ## 1.6.18.7
 
 * Fix functions generating Open Graph metadata[#1709](https://github.com/yesodweb/yesod/pull/1709)
diff --git a/test/YesodCoreTest/Widget.hs b/test/YesodCoreTest/Widget.hs
--- a/test/YesodCoreTest/Widget.hs
+++ b/test/YesodCoreTest/Widget.hs
@@ -98,7 +98,7 @@
     assertBody "<!DOCTYPE html>\n<html><head><title></title><script>toHead</script><toHead></toHead>\n<style>toWidget{bar:baz}toHead{bar:baz}</style></head><body><script>toBody</script><p>toWidget</p>\n<p>toBody</p>\n<script>toWidget</script></body></html>" res
 
 runner :: Session () -> IO ()
-runner f = toWaiApp Y >>= runSession f
+runner f = toWaiAppPlain Y >>= runSession f
 
 case_addJuliusBody :: IO ()
 case_addJuliusBody = runner $ do
diff --git a/yesod-core.cabal b/yesod-core.cabal
--- a/yesod-core.cabal
+++ b/yesod-core.cabal
@@ -1,5 +1,5 @@
 name:            yesod-core
-version:         1.6.18.7
+version:         1.6.18.8
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
