diff --git a/src/testdir/test_channel.py b/src/testdir/test_channel.py
index 227780a..b5a912c 100644
--- a/src/testdir/test_channel.py
+++ b/src/testdir/test_channel.py
@@ -73,6 +73,11 @@
                         print("sending: {0}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
+                    elif decoded[1] == 'bad command':
+                        cmd = '["ex","foo bar"]'
+                        print("sending: {0}".format(cmd))
+                        self.request.sendall(cmd.encode('utf-8'))
+                        response = "ok"
                     elif decoded[1] == 'do normal':
                         # Send a normal command.
                         cmd = '["normal","G$s more\u001b"]'
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index b356c88..7051223 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -151,6 +151,11 @@
   call assert_equal('added1', getline(line('$') - 1))
   call assert_equal('added2', getline('$'))
 
+  " Request command "foo bar", which fails silently.
+  call assert_equal('ok', ch_evalexpr(handle, 'bad command'))
+  call s:waitFor('v:errmsg =~ "E492"')
+  call assert_true(v:errmsg =~ 'E492:.*foo bar')
+
   call assert_equal('ok', ch_evalexpr(handle, 'do normal', {'timeout': 100}))
   call s:waitFor('"added more" == getline("$")')
   call assert_equal('added more', getline('$'))