diff --git a/core-program.cabal b/core-program.cabal
--- a/core-program.cabal
+++ b/core-program.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           core-program
-version:        0.6.5.0
+version:        0.6.5.1
 synopsis:       Opinionated Haskell Interoperability
 description:    A library to help build command-line programs, both tools and
                 longer-running daemons.
diff --git a/lib/Core/Program/Execute.hs b/lib/Core/Program/Execute.hs
--- a/lib/Core/Program/Execute.hs
+++ b/lib/Core/Program/Execute.hs
@@ -316,12 +316,12 @@
     -- drain. Allow 10 seconds, then timeout, in case something has gone
     -- wrong and queues don't empty.
 
-    _ <- forkIO $ do
+    t2 <- forkIO $ do
         threadDelay 10000000
         putStrLn "error: Timeout"
-        Safe.throw (ExitFailure 99)
+        Safe.throw (ExitFailure 96)
 
-    _ <- forkIO $ do
+    t3 <- forkIO $ do
         let scope = currentScopeFrom context
         pointers <- readTVarIO scope
         forM_ pointers killThread
@@ -338,7 +338,12 @@
 
     hFlush stdout
 
-    -- exiting this way avoids "Exception: ExitSuccess" noise in GHCi
+    -- exiting this way avoids "Exception: ExitSuccess" noise in GHCi, and
+    -- makes sure we don't have the timeout killer hanging around!
+
+    killThread t3
+    killThread t2
+
     if code == ExitSuccess
         then return ()
         else (Base.throwIO code)