diff --git a/src/Vervis/Darcs.hs b/src/Vervis/Darcs.hs
index ab37706..3093bbb 100644
--- a/src/Vervis/Darcs.hs
+++ b/src/Vervis/Darcs.hs
@@ -282,16 +282,15 @@ joinHunks =
 -- * The hash may or may not be found in the repo. If there's no patch in the
 --   repo with the given hash, 'Nothing' is returned.
 readPatch :: FilePath -> Text -> IO (Maybe Patch)
-readPatch path hash = do
+readPatch path hash = handle $ runExceptT $ do
     let pih = PatchInfoHash $ fst $ B16.decode $ encodeUtf8 hash
-    li <- handle =<< readLatestInventory path latestInventoryAllP
+    li <- ExceptT $ readLatestInventory path latestInventoryAllP
     mp <- loop pih (liPatches li) (fst <$> liPrevTag li)
     for mp $ \ (pi, pch) -> do
         (_pir, hunks) <-
-            handle =<< readCompressedPatch path pch (P.patch <* A.endOfInput)
-        let (an, ae) =
-                either error id $
-                A.parseOnly (author <* A.endOfInput) $ piAuthor pi
+            ExceptT $ readCompressedPatch path pch (P.patch <* A.endOfInput)
+        (an, ae) <-
+            ExceptT . pure $ A.parseOnly (author <* A.endOfInput) $ piAuthor pi
         return Patch
             { patchWritten     =
                 ( Author
@@ -307,7 +306,11 @@ readPatch path hash = do
                 map (mkedit . second joinHunks) $ groupHunksByFile hunks
             }
   where
-    handle = either (const $ fail "readPatch failed") pure
+    handle a = do
+        r <- a
+        case r of
+            Left e -> fail $ "readPatch failed: " ++ e
+            Right mp -> return mp
     lookup' pih ps = case F.find (\ (_pi, pih', _pch) -> pih' == pih) ps of
         Nothing              -> Nothing
         Just (pi, _pih, pch) -> Just (pi, pch)
@@ -316,7 +319,7 @@ readPatch path hash = do
         Nothing -> case mih of
             Nothing -> return Nothing
             Just ih -> do
-                i <- handle =<< readCompressedInventory path ih earlyInventoryAllP
+                i <- ExceptT $ readCompressedInventory path ih earlyInventoryAllP
                 case i of
                     Left ei  -> loop pih (eiPatches ei) Nothing
                     Right mi -> loop pih (miPatches mi) (Just $ miPrevious mi)