diff --git a/Assistant/ThreadedMonad.hs b/Assistant/ThreadedMonad.hs
index c4d331f61b..51f579d07f 100644
--- a/Assistant/ThreadedMonad.hs
+++ b/Assistant/ThreadedMonad.hs
@@ -11,6 +11,7 @@ import Common.Annex
 import qualified Annex
 
 import Control.Concurrent
+import Control.Exception (throw)
 
 {- The Annex state is stored in a MVar, so that threaded actions can access
  - it. -}
@@ -35,6 +36,9 @@ withThreadState a = do
 runThreadState :: ThreadState -> Annex a -> IO a
 runThreadState mvar a = do
 	startstate <- takeMVar mvar
-	!(r, newstate) <- Annex.run startstate a
+	-- catch IO errors and rethrow after restoring the MVar
+	!(r, newstate) <- catchIO (Annex.run startstate a) $ \e -> do
+		putMVar mvar startstate
+		throw e
 	putMVar mvar newstate
 	return r