--- a/build/upload.py
+++ b/build/upload.py
@@ -85,16 +85,18 @@ def AppendOptionalArgsToSSHCommandline(c
     commandline arguments to the list cmdline if the values are not None."""
     if port is not None:
         cmdline.append("-P%d" % port)
     if ssh_key is not None:
         # Don't interpret ~ paths - ssh can handle that on its own
         if not ssh_key.startswith('~'):
             ssh_key = WindowsPathToMsysPath(ssh_key)
         cmdline.extend(["-o", "IdentityFile=%s" % ssh_key])
+    # In case of an issue here we don't want to hang on a password prompt.
+    cmdline.extend(["-o", "BatchMode=yes"])
 
 def DoSSHCommand(command, user, host, port=None, ssh_key=None):
     """Execute command on user@host using ssh. Optionally use
     port and ssh_key, if provided."""
     cmdline = ["ssh"]
     AppendOptionalArgsToSSHCommandline(cmdline, port, ssh_key)
     cmdline.extend(["%s@%s" % (user, host), command])