diff --git a/src/channel.c b/src/channel.c
index 65757f1..c0572d3 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -1311,6 +1311,11 @@
     jobopt_T    opt;
     channel_T	*channel = NULL;
 
+    if (in_vim9script()
+	    && (check_for_string_arg(argvars, 0) == FAIL
+		|| check_for_dict_arg(argvars, 1) == FAIL))
+	return NULL;
+
     address = tv_get_string(&argvars[0]);
     if (argvars[1].v_type != VAR_UNKNOWN
 	 && (argvars[1].v_type != VAR_DICT || argvars[1].vval.v_dict == NULL))