diff --git a/src/option.c b/src/option.c
index 5a8af31..d948ac6 100644
--- a/src/option.c
+++ b/src/option.c
@@ -4612,7 +4612,7 @@
 				    || (long *)varp == &p_wcm)
 				&& (*arg == '<'
 				    || *arg == '^'
-				    || ((!arg[1] || vim_iswhite(arg[1]))
+				    || (*arg != NUL && (!arg[1] || vim_iswhite(arg[1]))
 					&& !VIM_ISDIGIT(*arg))))
 			{
 			    value = string_to_key(arg);
@@ -5843,7 +5843,7 @@
 							   opt_flags)) == NULL)
 	    did_set_option(opt_idx, opt_flags, TRUE);
 
-	/* call autocomamnd after handling side effects */
+	/* call autocommand after handling side effects */
 #if defined(FEAT_AUTOCMD) && defined(FEAT_EVAL)
 	if (saved_oldval != NULL)
 	{