diff --git a/src/option.c b/src/option.c
index 8a706af..348c37a 100644
--- a/src/option.c
+++ b/src/option.c
@@ -6951,6 +6951,8 @@
     {
 	if (check_opt_strings(p_cot, p_cot_values, TRUE) != OK)
 	    errmsg = e_invarg;
+	else
+	    completeopt_was_set();
     }
 #endif /* FEAT_INS_EXPAND */