diff --git a/src/wormhole/cli/cmd_send.py b/src/wormhole/cli/cmd_send.py
index 72e3a90..ffb6d02 100644
--- a/src/wormhole/cli/cmd_send.py
+++ b/src/wormhole/cli/cmd_send.py
@@ -130,6 +130,9 @@ class Sender:
             them_d = json.loads(them_d_bytes.decode("utf-8"))
             #print("GOT", them_d)
             recognized = False
+            if u"error" in them_d:
+                raise TransferError("remote error, transfer abandoned: %s"
+                                    % them_d["error"])
             if u"transit" in them_d:
                 recognized = True
                 yield self._handle_transit(them_d[u"transit"])
@@ -229,9 +232,6 @@ class Sender:
                 returnValue(None) # terminates this function
             raise TransferError("error sending text: %r" % (them_answer,))
 
-        if "error" in them_answer:
-            raise TransferError("remote error, transfer abandoned: %s"
-                                % them_answer["error"])
         if them_answer.get("file_ack") != "ok":
             raise TransferError("ambiguous response from remote, "
                                 "transfer abandoned: %s" % (them_answer,))
diff --git a/src/wormhole/test/test_scripts.py b/src/wormhole/test/test_scripts.py
index d3976cc..a2d042b 100644
--- a/src/wormhole/test/test_scripts.py
+++ b/src/wormhole/test/test_scripts.py
@@ -430,6 +430,93 @@ class PregeneratedCode(ServerBase, ScriptsBase, unittest.TestCase):
     def test_directory_override(self):
         return self._do_test(mode="directory", override_filename=True)
 
+    @inlineCallbacks
+    def test_file_noclobber(self):
+        common_args = ["--hide-progress", "--no-listen",
+                       "--relay-url", self.relayurl,
+                       "--transit-helper", ""]
+        code = u"1-abc"
+        message = "test message"
+
+        send_args = common_args + [ "send", "--code", code ]
+        receive_args = common_args + [ "receive", "--accept-file", code ]
+
+        send_dir = self.mktemp()
+        os.mkdir(send_dir)
+        receive_dir = self.mktemp()
+        os.mkdir(receive_dir)
+
+        send_filename = "testfile"
+        with open(os.path.join(send_dir, send_filename), "w") as f:
+            f.write(message)
+        send_args.append(send_filename)
+        receive_filename = send_filename
+
+        PRESERVE = "don't clobber me\n"
+        clobberable = os.path.join(receive_dir, receive_filename)
+        with open(clobberable, "w") as f:
+            f.write(PRESERVE)
+
+        sargs = runner.parser.parse_args(send_args)
+        sargs.cwd = send_dir
+        sargs.stdout = io.StringIO()
+        sargs.stderr = io.StringIO()
+        sargs.timing = DebugTiming()
+        rargs = runner.parser.parse_args(receive_args)
+        rargs.cwd = receive_dir
+        rargs.stdout = io.StringIO()
+        rargs.stderr = io.StringIO()
+        rargs.timing = DebugTiming()
+        send_d = cmd_send.send(sargs)
+        receive_d = cmd_receive.receive(rargs)
+
+        # both sides will fail because of the pre-existing file
+
+        f = yield self.assertFailure(send_d, TransferError)
+        self.assertEqual(str(f), "remote error, transfer abandoned: file already exists")
+
+        f = yield self.assertFailure(receive_d, TransferError)
+        self.assertEqual(str(f), "file already exists")
+
+        send_stdout = sargs.stdout.getvalue()
+        send_stderr = sargs.stderr.getvalue()
+        receive_stdout = rargs.stdout.getvalue()
+        receive_stderr = rargs.stderr.getvalue()
+
+        # all output here comes from a StringIO, which uses \n for
+        # newlines, even if we're on windows
+        NL = "\n"
+
+        self.maxDiff = None # show full output for assertion failures
+
+        self.failUnlessEqual(send_stderr, "",
+                             (send_stdout, send_stderr))
+        self.failUnlessEqual(receive_stderr, "",
+                             (receive_stdout, receive_stderr))
+
+        # check sender
+        self.failUnlessIn("Sending {bytes:d} byte file named '{name}'{NL}"
+                          .format(bytes=len(message), name=send_filename,
+                                  NL=NL), send_stdout)
+        self.failUnlessIn("On the other computer, please run: "
+                          "wormhole receive{NL}"
+                          "Wormhole code is: {code}{NL}{NL}"
+                          .format(code=code, NL=NL),
+                          send_stdout)
+        self.failIfIn("File sent.. waiting for confirmation{NL}"
+                      "Confirmation received. Transfer complete.{NL}"
+                      .format(NL=NL), send_stdout)
+
+        # check receiver
+        self.failUnlessIn("Error: "
+                          "refusing to overwrite existing file testfile{NL}"
+                          .format(NL=NL), receive_stdout)
+        self.failIfIn("Received file written to ", receive_stdout)
+        fn = os.path.join(receive_dir, receive_filename)
+        self.failUnless(os.path.exists(fn))
+        with open(fn, "r") as f:
+            self.failUnlessEqual(f.read(), PRESERVE)
+
 class Cleanup(ServerBase, unittest.TestCase):
     @inlineCallbacks
     def test_text(self):