diff --git a/include/PrimaryGeneratorAction.h b/include/PrimaryGeneratorAction.h
index 797a396..f184f7f 100644
--- a/include/PrimaryGeneratorAction.h
+++ b/include/PrimaryGeneratorAction.h
@@ -19,7 +19,7 @@ public:
     const G4ParticleGun* GetParticleGun() const { return fParticleGun; };
 
 private:
-    G4String particleType;
+    G4String particleType = "NULL";
     G4ParticleGun* fParticleGun = nullptr;
 };
 
diff --git a/src/PrimaryGeneratorAction.cpp b/src/PrimaryGeneratorAction.cpp
index 913e4d5..9f34174 100644
--- a/src/PrimaryGeneratorAction.cpp
+++ b/src/PrimaryGeneratorAction.cpp
@@ -18,8 +18,6 @@ PrimaryGeneratorAction::PrimaryGeneratorAction() {
         (DetectorConstruction*)(G4RunManager::GetRunManager()->GetUserDetectorConstruction());
 
     fParticleGun = new G4ParticleGun();
-    particleType = detConstruction->GetParticleType();
-    DefineParticle(particleType);
 }
 
 PrimaryGeneratorAction::~PrimaryGeneratorAction() { delete fParticleGun; }