@@ -128,6 +128,7 @@ def readline_channel(self, channel, timeout=None):
                 return b"" if self.binary else ""
 
             self.update(timeout=(timeout - time.time() + start))
+        return b"" if self.binary else ""
 
     def write_channel(self, channel, data):
         """Write data to a channel."""
@@ -216,11 +217,15 @@ def update(self, timeout=0):
         if hasattr(select, "poll"):
             poll = select.poll()
             poll.register(self.sock.sock, select.POLLIN)
-            if timeout is not None:
+            if timeout is not None and timeout != float("inf"):
                 timeout *= 1_000  # poll method uses milliseconds as the time unit
+            else:
+                timeout = None
             r = poll.poll(timeout)
             poll.unregister(self.sock.sock)
         else:
+            if timeout == float("inf"):
+                timeout = None
             r, _, _ = select.select(
                 (self.sock.sock, ), (), (), timeout)