diff --git a/src/terminal.c b/src/terminal.c
index e3945d0..9de516c 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -5276,6 +5276,11 @@
     FILE	*fd2 = NULL;
     char_u	*textline = NULL;
 
+    if (in_vim9script()
+	    && (check_for_string_arg(argvars, 0) == FAIL
+		|| check_for_dict_arg(argvars, 1) == FAIL))
+	return;
+
     // First open the files.  If this fails bail out.
     fname1 = tv_get_string_buf_chk(&argvars[0], buf1);
     if (do_diff)