diff --git a/epan/dissectors/packet-tcap.c b/epan/dissectors/packet-tcap.c
index bb04eaecc8..4d3db45e0c 100644
--- a/epan/dissectors/packet-tcap.c
+++ b/epan/dissectors/packet-tcap.c
@@ -2041,7 +2041,7 @@ dissect_tcap_dialog_portion(ASN1_SCK *asn1, proto_tree *tcap_tree, proto_item *t
 
     if (portion_def_len)
     {
-	tvb_ensure_bytes_exist(tcap_tree, saved_offset, len);
+	tvb_ensure_bytes_exist(asn1->tvb, saved_offset, len);
 	proto_item_set_len(dlg_item, len);
     }