diff --git a/src/SystemBuilder.cc b/src/SystemBuilder.cc
index 48d5cf6..a062ce4 100644
--- a/src/SystemBuilder.cc
+++ b/src/SystemBuilder.cc
@@ -62,7 +62,7 @@ void SystemBuilder::run_gui(){
 void SystemBuilder::run_batch(int nEvents, std::string partSpecies, double minEnergy, double maxEnergy){
     G4String partSpec = (G4String)partSpecies;
     G4cout << "running with particle species " << partSpec << G4endl;
-    actionInitialization->setGeneratorProperties(minEnergy, maxEnergy, partSpec;
+    actionInitialization->setGeneratorProperties(minEnergy, maxEnergy, partSpec);
     UImanager->ApplyCommand("/run/initialize");
     runManager->BeamOn(nEvents);
 }
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