diff --git a/Yesod/Persist/Core.hs b/Yesod/Persist/Core.hs
--- a/Yesod/Persist/Core.hs
+++ b/Yesod/Persist/Core.hs
@@ -28,6 +28,8 @@
 import Data.IORef.Lifted
 import Data.Conduit.Pool
 import Control.Monad.Trans.Resource
+import Control.Exception (throwIO)
+import Yesod.Core.Types (HandlerContents (HCError))
 import qualified Database.Persist.Sql as SQL
 
 type YesodDB site = YesodPersistBackend site (HandlerT site IO)
@@ -132,7 +134,7 @@
 get404 key = do
     mres <- get key
     case mres of
-        Nothing -> lift notFound
+        Nothing -> notFound'
         Just res -> return res
 
 -- | Get the given entity by unique key, or return a 404 not found if it doesn't
@@ -148,8 +150,13 @@
 getBy404 key = do
     mres <- getBy key
     case mres of
-        Nothing -> lift notFound
+        Nothing -> notFound'
         Just res -> return res
+
+-- | Should be equivalent to @lift . notFound@, but there's an apparent bug in
+-- GHC 7.4.2 that leads to segfaults. This is a workaround.
+notFound' :: MonadIO m => m a
+notFound' = liftIO $ throwIO $ HCError NotFound
 
 instance MonadHandler m => MonadHandler (SqlPersistT m) where
     type HandlerSite (SqlPersistT m) = HandlerSite m
diff --git a/yesod-persistent.cabal b/yesod-persistent.cabal
--- a/yesod-persistent.cabal
+++ b/yesod-persistent.cabal
@@ -1,5 +1,5 @@
 name:            yesod-persistent
-version:         1.2.1
+version:         1.2.2
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>