From f96a628a178e329de2224d7594749dd608195a14 Mon Sep 17 00:00:00 2001
From: David Griffith <dave@661.org>
Date: Sat, 13 Jul 2019 00:19:52 -0700
Subject: [PATCH] get_prop_len opcode returns 0 when argument is 0 per
 Z-machine spec 1.1.

Copied from Windows Frotz.
---
 src/common/object.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/common/object.c b/src/common/object.c
index d2dc7e6..699035b 100644
--- a/src/common/object.c
+++ b/src/common/object.c
@@ -667,6 +667,11 @@ void z_get_prop_len (void)
     zword addr;
     zbyte value;
 
+    if (zargs[0] == 0) {
+	store (0); /* demanded by Spec 1.1 */
+	return;
+    }
+
     /* Back up the property pointer to the property id */
 
     addr = zargs[0] - 1;
-- 
2.34.1