--- a/src/channel.c
+++ b/src/channel.c
@@ -4720,6 +4720,111 @@ job_still_useful(job_T *job)
     return job_need_end_check(job) || job_channel_still_useful(job);
 }
 
+#if !defined(USE_ARGV) || defined(PROTO)
+/*
+ * Escape one argument for an external command.
+ * Returns the escaped string in allocated memory.  NULL when out of memory.
+ */
+    static char_u *
+win32_escape_arg(char_u *arg)
+{
+    int		slen, dlen;
+    int		escaping = 0;
+    int		i;
+    char_u	*s, *d;
+    char_u	*escaped_arg;
+    int		has_spaces = FALSE;
+
+    /* First count the number of extra bytes required. */
+    slen = STRLEN(arg);
+    dlen = slen;
+    for (s = arg; *s != NUL; MB_PTR_ADV(s))
+    {
+	if (*s == '"' || *s == '\\')
+	    ++dlen;
+	if (*s == ' ' || *s == '\t')
+	    has_spaces = TRUE;
+    }
+
+    if (has_spaces)
+	dlen += 2;
+
+    if (dlen == slen)
+	return vim_strsave(arg);
+
+    /* Allocate memory for the result and fill it. */
+    escaped_arg = alloc(dlen + 1);
+    if (escaped_arg == NULL)
+	return NULL;
+    memset(escaped_arg, 0, dlen+1);
+
+    d = escaped_arg;
+
+    if (has_spaces)
+	*d++ = '"';
+
+    for (s = arg; *s != NUL;)
+    {
+	switch (*s)
+	{
+	    case '"':
+		for (i = 0; i < escaping; i++)
+		    *d++ = '\\';
+		escaping = 0;
+		*d++ = '\\';
+		*d++ = *s++;
+		break;
+	    case '\\':
+		escaping++;
+		*d++ = *s++;
+		break;
+	    default:
+		escaping = 0;
+		MB_COPY_CHAR(s, d);
+		break;
+	}
+    }
+
+    /* add terminating quote and finish with a NUL */
+    if (has_spaces)
+    {
+	for (i = 0; i < escaping; i++)
+	    *d++ = '\\';
+	*d++ = '"';
+    }
+    *d = NUL;
+
+    return escaped_arg;
+}
+
+/*
+ * Build a command line from a list, taking care of escaping.
+ * The result is put in gap->ga_data.
+ * Returns FAIL when out of memory.
+ */
+    int
+win32_build_cmd(list_T *l, garray_T *gap)
+{
+    listitem_T  *li;
+    char_u	*s;
+
+    for (li = l->lv_first; li != NULL; li = li->li_next)
+    {
+	s = get_tv_string_chk(&li->li_tv);
+	if (s == NULL)
+	    return FAIL;
+	s = win32_escape_arg(s);
+	if (s == NULL)
+	    return FAIL;
+	ga_concat(gap, s);
+	vim_free(s);
+	if (li->li_next != NULL)
+	    ga_append(gap, ' ');
+    }
+    return OK;
+}
+#endif
+
 /*
  * NOTE: Must call job_cleanup() only once right after the status of "job"
  * changed to JOB_ENDED (i.e. after job_status() returned "dead" first or
@@ -5093,51 +5198,25 @@ job_start(typval_T *argvars, jobopt_T *o
     else
     {
 	list_T	    *l = argvars[0].vval.v_list;
+#ifdef USE_ARGV
 	listitem_T  *li;
 	char_u	    *s;
 
-#ifdef USE_ARGV
 	/* Pass argv[] to mch_call_shell(). */
 	argv = (char **)alloc(sizeof(char *) * (l->lv_len + 1));
 	if (argv == NULL)
 	    goto theend;
-#endif
 	for (li = l->lv_first; li != NULL; li = li->li_next)
 	{
 	    s = get_tv_string_chk(&li->li_tv);
 	    if (s == NULL)
 		goto theend;
-#ifdef USE_ARGV
 	    argv[argc++] = (char *)s;
-#else
-	    /* Only escape when needed, double quotes are not always allowed. */
-	    if (li != l->lv_first && vim_strpbrk(s, (char_u *)" \t\"") != NULL)
-	    {
-# ifdef WIN32
-		int old_ssl = p_ssl;
-
-		/* This is using CreateProcess, not cmd.exe.  Always use
-		 * double quote and backslashes. */
-		p_ssl = 0;
-# endif
-		s = vim_strsave_shellescape(s, FALSE, TRUE);
-# ifdef WIN32
-		p_ssl = old_ssl;
-# endif
-		if (s == NULL)
-		    goto theend;
-		ga_concat(&ga, s);
-		vim_free(s);
-	    }
-	    else
-		ga_concat(&ga, s);
-	    if (li->li_next != NULL)
-		ga_append(&ga, ' ');
-#endif
 	}
-#ifdef USE_ARGV
 	argv[argc] = NULL;
 #else
+	if (win32_build_cmd(l, &ga) == FAIL)
+	    goto theend;
 	cmd = ga.ga_data;
 #endif
     }