diff --git a/src/channel.c b/src/channel.c
index 22f63b3..ccab2cb 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -3812,6 +3812,11 @@
     {
 	/* Command is a string. */
 	cmd = argvars[0].vval.v_string;
+	if (cmd == NULL || *cmd == NUL)
+	{
+	    EMSG(_(e_invarg));
+	    return job;
+	}
 #ifdef USE_ARGV
 	if (mch_parse_cmd(cmd, FALSE, &argv, &argc) == FAIL)
 	    return job;
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index 94311e9..8356ba7 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -1201,5 +1201,10 @@
   call s:run_server('s:test_close_callback')
 endfunc
 
+func Test_job_start_invalid()
+  call assert_fails('call job_start($x)', 'E474:')
+  call assert_fails('call job_start("")', 'E474:')
+endfunc
+
 " Uncomment this to see what happens, output is in src/testdir/channellog.
 " call ch_logfile('channellog', 'w')
diff --git a/src/version.c b/src/version.c
index e925e41..e183717 100644
--- a/src/version.c
+++ b/src/version.c
@@ -749,6 +749,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1665,
+/**/
     1664,
 /**/
     1663,