diff --git a/Annex/Ssh.hs b/Annex/Ssh.hs
index b913c154c1..7bb9ad0f2e 100644
--- a/Annex/Ssh.hs
+++ b/Annex/Ssh.hs
@@ -34,7 +34,6 @@ import Annex.Path
 import Utility.Env
 import Utility.FileSystemEncoding
 import Utility.Hash
-import Utility.Process.Transcript
 import Types.CleanupActions
 import Types.Concurrency
 import Git.Env
@@ -219,13 +218,17 @@ prepSocket socketfile gc sshhost sshparams = do
 	-- return True.
 	-- (Except there's an unlikely false positive where a forced
 	-- ssh command exits 255.)
-	tryssh extraps = liftIO $ do
+	tryssh extraps = liftIO $ withNullHandle $ \nullh -> do
 		let p = proc "ssh" $ concat
 			[ extraps
 			, toCommand sshparams
 			, [fromSshHost sshhost, "true"]
 			]
-		(_, exitcode) <- processTranscript'' p Nothing
+		(Nothing, Nothing, Nothing, pid) <- createProcess $ p
+			{ std_out = UseHandle nullh
+			, std_err = UseHandle nullh
+			}
+		exitcode <- waitForProcess pid
 		return $ case exitcode of
 			ExitFailure 255 -> False
 			_ -> True
diff --git a/CHANGELOG b/CHANGELOG
index 17db60cc42..d6f710a411 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -33,6 +33,9 @@ git-annex (6.20180228) UNRELEASED; urgency=medium
     the only copy of a file when it thought the tor remote had a copy.
   * Better ssh connection warmup when using -J for concurrency.
     Avoids ugly messages when forced ssh command is not git-annex-shell.
+  * Fix race condition in ssh warmup that caused git-annex to get
+    stuck and never process some while when run with high levels of
+    concurrency.
   * Note that Remote/Git.hs now contains AGPL licensed code,
     thus the license of git-annex as a whole is AGPL. This was already
     the case when git-annex was built with the webapp enabled.
diff --git a/doc/bugs/occasional_hang_with_p2pstdio.mdwn b/doc/bugs/occasional_hang_with_p2pstdio.mdwn
index bdfce1fe4c..a46e59c35d 100644
--- a/doc/bugs/occasional_hang_with_p2pstdio.mdwn
+++ b/doc/bugs/occasional_hang_with_p2pstdio.mdwn
@@ -29,3 +29,26 @@ Interestingly, the debug log shows it only ran git-annex-shell p2pstdio
 6 times, despite the concurrency of 20. So, the other 14 must have stalled
 setting up the connection. Suggests the bug is in the connection pool
 code.
+
+> The hang does not involve the connection pool code itself; a call to
+> Annex.Ssh.sshCommand is hanging. So, this likely affected git-annex
+> before p2pstdio, although its timings of calls to sshCommand may be
+> exposing the problem.
+> 
+> The hang is in prepSocket; all the threads enter makeconnection near the
+> same time, and so all of them try to warm up the ssh connection at the
+> same time. And somehow many of those executions of ssh hang.
+> (Arguably there should be locking to prevent multiple threads doing
+> this, but the actual overhead of multiple threads doing it may be
+> smaller than the overhead of such added locking.)
+>
+> Why is makeconnection's use of processTranscript hanging?
+> processTranscriot tries to read the process's output (ssh has none),
+> and waiting for the output to get read is for some reason hanging
+> forever, despite the ssh process becoming a zombie.
+> Converted makeconnection to not use processTranscript,
+> and that does seem to avoid the hang.
+>
+> So, this bug is left open only because processTranscript hangs in situations
+> like this. No other uses of it involve concurrency, but we still need to
+> get to the bottom of its hang.. --[[Joey]]