diff --git a/NPSimulation/Detectors/Minos/Minos.cc b/NPSimulation/Detectors/Minos/Minos.cc
index 5446d1bed8da9063ed724ca88cf5cefab77d148c..bd69efc44678b0b09c59c65ba526a7be8e64198c 100644
--- a/NPSimulation/Detectors/Minos/Minos.cc
+++ b/NPSimulation/Detectors/Minos/Minos.cc
@@ -675,7 +675,7 @@ void Minos::ConstructDetector(G4LogicalVolume* world){
     // }
 
     new G4PVPlacement(0,//its name
-        G4ThreeVector(wX,wY, wZ + ChamberLength - m_TargetLength[i]-WindowThickness*2. + 11*mm ),	// Z positioning putting TPC beginn and Target beginning w/ difference of 11mm 
+        G4ThreeVector(wX,wY, wZ + ChamberLength - m_TargetLength[i]-WindowThickness*2. - 11*mm ),	// Z positioning putting TPC beginn and Target beginning w/ difference of 11mm 
         BuildTPC(),	//its logical volume
         "TPC",	//its name
         world,	//its mother  volume