diff --git a/bacnet-stack/src/bacdevobjpropref.c b/bacnet-stack/src/bacdevobjpropref.c
index 841c3d60..f5c11b03 100644
--- a/bacnet-stack/src/bacdevobjpropref.c
+++ b/bacnet-stack/src/bacdevobjpropref.c
@@ -1,4 +1,4 @@
-/*####COPYRIGHTBEGIN####
+index/*####COPYRIGHTBEGIN####
  -------------------------------------------
  Copyright (C) 2008 John Minack
 
@@ -78,7 +78,7 @@ int bacapp_encode_device_obj_property_ref(
     apdu_len += len;
 
     /* Array index is optional so check if needed before inserting */
-    if (value->arrayIndex > 0) {
+    if (value->arrayIndex != BACNET_ARRAY_ALL) {
         len = encode_context_unsigned(&apdu[apdu_len], 2, value->arrayIndex);
         apdu_len += len;
     }