diff --git a/CHANGELOG b/CHANGELOG
index 41196c28d8..a4b255dce7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,7 @@
 git-annex (7.20181032) UNRELEASED; urgency=medium
 
   * Increase minimum QuickCheck version.
+  * Fix a P2P protocol hang.
 
  -- Joey Hess <id@joeyh.name>  Wed, 31 Oct 2018 15:53:03 -0400
 
diff --git a/P2P/Annex.hs b/P2P/Annex.hs
index c89ef93a1e..a08b923176 100644
--- a/P2P/Annex.hs
+++ b/P2P/Annex.hs
@@ -50,18 +50,19 @@ runLocal runst runner a = case a of
 		size <- inAnnex' isJust Nothing getsize k
 		runner (next (Len <$> size))
 	ReadContent k af o sender next -> do
+		let proceed c = do
+			r <- tryNonAsync c
+			case r of
+				Left e -> return $ Left $ ProtoFailureException e
+				Right (Left e) -> return $ Left e
+				Right (Right ok) -> runner (next ok)
 		v <- tryNonAsync $ prepSendAnnex k
 		case v of
-			Right (Just (f, checkchanged)) -> do
-				v' <- tryNonAsync $
-					transfer upload k af $
-						sinkfile f o checkchanged sender
-				case v' of
-					Left e -> return $ Left $ ProtoFailureException e
-					Right (Left e) -> return $ Left e
-					Right (Right ok) -> runner (next ok)
-			-- content not available
- 			Right Nothing -> runner (next False)
+			Right (Just (f, checkchanged)) -> proceed $
+				transfer upload k af $
+					sinkfile f o checkchanged sender
+ 			Right Nothing -> proceed $
+				runner (sender mempty (return Invalid))
 			Left e -> return $ Left $ ProtoFailureException e
 	StoreContent k af o l getb validitycheck next -> do
 		-- This is the same as the retrievalSecurityPolicy of
diff --git a/P2P/Protocol.hs b/P2P/Protocol.hs
index 49a3d5bf6f..6e2d7fc81e 100644
--- a/P2P/Protocol.hs
+++ b/P2P/Protocol.hs
@@ -238,8 +238,9 @@ data LocalF c
 	-- present.
 	| ReadContent Key AssociatedFile Offset (L.ByteString -> Proto Validity -> Proto Bool) (Bool -> c)
 	-- ^ Reads the content of a key and sends it to the callback.
-	-- If the content is not available, sends L.empty to the callback.
-	-- Note that the content may change while it's being sent.
+	-- May send any amount of data, including L.empty if the content is
+	-- not available. The callback must deal with that.
+	-- And the content may change while it's being sent.
 	-- The callback is passed a validity check that it can run after
 	-- sending the content to detect when this happened.
 	| StoreContent Key AssociatedFile Offset Len (Proto L.ByteString) (Proto (Maybe Validity)) (Bool -> c)