diff --git a/src/channel.c b/src/channel.c
index f1c2ccd..ebbc315 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -5921,7 +5921,7 @@
     {
 	// Command is a string.
 	cmd = argvars[0].vval.v_string;
-	if (cmd == NULL || *cmd == NUL)
+	if (cmd == NULL || *skipwhite(cmd) == NUL)
 	{
 	    emsg(_(e_invarg));
 	    goto theend;
@@ -5945,13 +5945,12 @@
 	    goto theend;
 
 	// Empty command is invalid.
-#ifdef USE_ARGV
 	if (argc == 0 || *skipwhite((char_u *)argv[0]) == NUL)
 	{
 	    emsg(_(e_invarg));
 	    goto theend;
 	}
-#else
+#ifndef USE_ARGV
 	if (win32_build_cmd(l, &ga) == FAIL)
 	    goto theend;
 	cmd = ga.ga_data;