diff --git a/epan/expert.c b/epan/expert.c
index 32a5d4b27d..b9737d4e4d 100644
--- a/epan/expert.c
+++ b/epan/expert.c
@@ -641,9 +641,7 @@ proto_tree_add_expert_internal(proto_tree *tree, packet_info *pinfo, expert_fiel
 	va_end(unused);
 
 	/* But make sure it throws an exception *after* adding the item */
-	if (length == -1) {
-		length = tvb_captured_length(tvb) ? tvb_ensure_captured_length_remaining(tvb, start) : 0;
-	} else {
+	if (length != -1) {
 		tvb_ensure_bytes_exist(tvb, start, length);
 	}
 	return ti;
@@ -684,9 +682,7 @@ proto_tree_add_expert_format(proto_tree *tree, packet_info *pinfo, expert_field
 	va_end(ap);
 
 	/* But make sure it throws an exception *after* adding the item */
-	if (length == -1) {
-		length = tvb_captured_length(tvb) ? tvb_ensure_captured_length_remaining(tvb, start) : 0;
-	} else {
+	if (length != -1) {
 		tvb_ensure_bytes_exist(tvb, start, length);
 	}
 	return ti;