From e1f177e40d2a55178b4e9cd8a7c338a1bbc56697 Mon Sep 17 00:00:00 2001
From: AJPfleger <alexander.julian.pfleger@cern.ch>
Date: Mon, 30 Sep 2024 22:13:54 +0200
Subject: [PATCH] fix

---
 Examples/Algorithms/Geant4/src/MaterialSteppingAction.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Examples/Algorithms/Geant4/src/MaterialSteppingAction.cpp b/Examples/Algorithms/Geant4/src/MaterialSteppingAction.cpp
index ff00221b401..a6d8b8ed25a 100644
--- a/Examples/Algorithms/Geant4/src/MaterialSteppingAction.cpp
+++ b/Examples/Algorithms/Geant4/src/MaterialSteppingAction.cpp
@@ -97,7 +97,7 @@ void ActsExamples::MaterialSteppingAction::UserSteppingAction(
   G4Track* g4Track = step->GetTrack();
   std::size_t trackID = g4Track->GetTrackID();
   auto& materialTracks = eventStore().materialTracks;
-  if (materialTracks.contains(trackID - 1)) {
+  if (!materialTracks.contains(trackID - 1)) {
     Acts::RecordedMaterialTrack rmTrack;
     const auto& g4Vertex = g4Track->GetVertexPosition();
     Acts::Vector3 vertex(g4Vertex[0], g4Vertex[1], g4Vertex[2]);