diff --git a/psshlib/askpass_server.py b/psshlib/askpass_server.py
index 4293164..0104bb8 100644
--- a/psshlib/askpass_server.py
+++ b/psshlib/askpass_server.py
@@ -68,6 +68,7 @@ def handle_listen(self, fd, iomap):
     def handle_write(self, fd, iomap):
         buffer = self.buffermap[fd]
         conn = self.socketmap[fd]
+        bytes_written = 0
         try:
             bytes_written = conn.send(buffer)
         except socket.error: