1 files changed, 1 insertions, 1 deletions

diff --git a/src/Network/BitTorrent/Sessions.hs b/src/Network/BitTorrent/Sessions.hs
index ba0c60a1..f2035066 100644
--- a/src/Network/BitTorrent/Sessions.hs
+++ b/src/Network/BitTorrent/Sessions.hs
@@ -300,7 +300,7 @@ enterSwarm SwarmSession {..} = do
   MSem.wait vacantPeers
 
 leaveSwarm :: SwarmSession -> IO ()
-leaveSwarm SwarmSession {..} = do
+leaveSwarm SwarmSession {..} = mask_ $ do
   MSem.signal vacantPeers
   MSem.signal (activeThreads clientSession)