diff --git a/firmware/application/app_ert.cpp b/firmware/application/app_ert.cpp
index 5996c0a02..0000716f7 100644
--- a/firmware/application/app_ert.cpp
+++ b/firmware/application/app_ert.cpp
@@ -35,7 +35,7 @@ using namespace lpc43xx;
 namespace ert {
 
 size_t Packet::length() const {
-	return packet_.size();
+	return decoder_.symbols_count();
 }
 
 bool Packet::is_valid() const {