diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # ChangeLog for yesod-core
 
+## 1.6.19.0
+
+* Change order of priority in `languages`[#1721](https://github.com/yesodweb/yesod/pull/1721)
+
 ## 1.6.18.8
 
 * Fix test suite for wai-extra change around vary header
diff --git a/src/Yesod/Core/Handler.hs b/src/Yesod/Core/Handler.hs
--- a/src/Yesod/Core/Handler.hs
+++ b/src/Yesod/Core/Handler.hs
@@ -1226,10 +1226,10 @@
 -- Languages are determined based on the following (in descending order
 -- of preference):
 --
--- * The _LANG user session variable.
---
 -- * The _LANG get parameter.
 --
+-- * The _LANG user session variable.
+--
 -- * The _LANG cookie.
 --
 -- * Accept-Language HTTP header.
@@ -1238,11 +1238,12 @@
 -- If a matching language is not found the default language will be used.
 --
 -- This is handled by parseWaiRequest (not exposed).
+--
+-- __NOTE__: Before version @1.6.19.0@, this function prioritized the session
+-- variable above all other sources.
+--
 languages :: MonadHandler m => m [Text]
-languages = do
-    mlang <- lookupSession langKey
-    langs <- reqLangs <$> getRequest
-    return $ maybe id (:) mlang langs
+languages = reqLangs <$> getRequest
 
 lookup' :: Eq a => a -> [(a, b)] -> [b]
 lookup' a = map snd . filter (\x -> a == fst x)
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:         1.6.18.8
+version:         1.6.19.0
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>