diff --git a/src/vim9script.c b/src/vim9script.c
index faee131..05977b6 100644
--- a/src/vim9script.c
+++ b/src/vim9script.c
@@ -102,6 +102,7 @@
 	    case CMD_append:
 	    case CMD_change:
 	    case CMD_insert:
+	    case CMD_open:
 	    case CMD_t:
 	    case CMD_xit:
 		semsg(_(e_command_not_supported_in_vim9_script_missing_var_str), eap->cmd);