diff --git a/Yesod/Core/Internal/Run.hs b/Yesod/Core/Internal/Run.hs
--- a/Yesod/Core/Internal/Run.hs
+++ b/Yesod/Core/Internal/Run.hs
@@ -10,7 +10,8 @@
 import Yesod.Core.Internal.Response
 import           Blaze.ByteString.Builder     (toByteString)
 import           Control.Applicative          ((<$>))
-import           Control.Exception            (fromException, bracketOnError)
+import           Control.Exception            (fromException, bracketOnError, evaluate)
+import qualified Control.Exception            as E
 import           Control.Exception.Lifted     (catch)
 import           Control.Monad.IO.Class       (MonadIO)
 import           Control.Monad.IO.Class       (liftIO)
@@ -94,7 +95,9 @@
                 YRWai _ -> return yar
     let sendFile' ct fp p =
             return $ YRPlain H.status200 (appEndo headers []) ct (ContentFile fp p) finalSession
-    case contents of
+    contents1 <- evaluate contents `E.catch` \e -> return
+        (HCError $! InternalError $! T.pack $! show (e :: E.SomeException))
+    case contents1 of
         HCContent status (TypedContent ct c) -> do
             ec' <- liftIO $ evaluateContent c
             case ec' of
diff --git a/test/YesodCoreTest/ErrorHandling.hs b/test/YesodCoreTest/ErrorHandling.hs
--- a/test/YesodCoreTest/ErrorHandling.hs
+++ b/test/YesodCoreTest/ErrorHandling.hs
@@ -24,6 +24,11 @@
 /error-in-body ErrorInBodyR GET
 /error-in-body-noeval ErrorInBodyNoEvalR GET
 /override-status OverrideStatusR GET
+
+-- https://github.com/yesodweb/yesod/issues/658
+/builder BuilderR GET
+/file-bad-len FileBadLenR GET
+/file-bad-name FileBadNameR GET
 |]
 
 overrideStatus = mkStatus 15 "OVERRIDE"
@@ -74,6 +79,15 @@
 getOverrideStatusR :: Handler ()
 getOverrideStatusR = invalidArgs ["OVERRIDE"]
 
+getBuilderR :: Handler TypedContent
+getBuilderR = return $ TypedContent "ignored" $ ContentBuilder (error "builder-3.14159") Nothing
+
+getFileBadLenR :: Handler TypedContent
+getFileBadLenR = return $ TypedContent "ignored" $ ContentFile "yesod-core.cabal" (error "filebadlen")
+
+getFileBadNameR :: Handler TypedContent
+getFileBadNameR = return $ TypedContent "ignored" $ ContentFile (error "filebadname") Nothing
+
 errorHandlingTest :: Spec
 errorHandlingTest = describe "Test.ErrorHandling" $ do
       it "says not found" caseNotFound
@@ -82,6 +96,9 @@
       it "error in body == 500" caseErrorInBody
       it "error in body, no eval == 200" caseErrorInBodyNoEval
       it "can override status code" caseOverrideStatus
+      it "builder" caseBuilder
+      it "file with bad len" caseFileBadLen
+      it "file with bad name" caseFileBadName
 
 runner :: Session () -> IO ()
 runner f = toWaiApp App >>= runSession f
@@ -140,3 +157,21 @@
 caseOverrideStatus = runner $ do
     res <- request defaultRequest { pathInfo = ["override-status"] }
     assertStatus 15 res
+
+caseBuilder :: IO ()
+caseBuilder = runner $ do
+    res <- request defaultRequest { pathInfo = ["builder"] }
+    assertStatus 500 res
+    assertBodyContains "builder-3.14159" res
+
+caseFileBadLen :: IO ()
+caseFileBadLen = runner $ do
+    res <- request defaultRequest { pathInfo = ["file-bad-len"] }
+    assertStatus 500 res
+    assertBodyContains "filebadlen" res
+
+caseFileBadName :: IO ()
+caseFileBadName = runner $ do
+    res <- request defaultRequest { pathInfo = ["file-bad-name"] }
+    assertStatus 500 res
+    assertBodyContains "filebadname" res
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:         1.2.6.5
+version:         1.2.6.6
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>