diff --git a/include/RMGVertexConfinement.hh b/include/RMGVertexConfinement.hh
index 5a22e4d7..6166affc 100644
--- a/include/RMGVertexConfinement.hh
+++ b/include/RMGVertexConfinement.hh
@@ -154,6 +154,7 @@ class RMGVertexConfinement : public RMGVVertexGenerator {
 
     SamplingMode fSamplingMode = kUnionAll;
     bool fOnSurface = false;
+    bool fForceContainmentCheck = false;
 
     // counters used for the current run.
     long fTrials = 0;
diff --git a/src/RMGVertexConfinement.cc b/src/RMGVertexConfinement.cc
index 1563f22b..ab61acf4 100644
--- a/src/RMGVertexConfinement.cc
+++ b/src/RMGVertexConfinement.cc
@@ -388,6 +388,7 @@ void RMGVertexConfinement::Reset() {
   fGeomVolumeSolids.clear();
   fSamplingMode = RMGVertexConfinement::kUnionAll;
   fOnSurface = false;
+  fForceContainmentCheck = false;
 }
 
 bool RMGVertexConfinement::GenerateVertex(G4ThreeVector& vertex) {
@@ -459,6 +460,14 @@ bool RMGVertexConfinement::ActualGenerateVertex(G4ThreeVector& vertex) {
         } else {
           vertex = choice.translation +
                    choice.rotation * RMGGeneratorUtil::rand(choice.sampling_solid, fOnSurface);
+          if (fForceContainmentCheck) {
+            auto is_inside = physical_first ? fPhysicalVolumes.IsInside(vertex)
+                                            : fGeomVolumeSolids.IsInside(vertex);
+            if (!is_inside)
+              RMGLog::OutDev(RMGLog::error,
+                  "Generated vertex not inside sampling volumes (forced containment check): ",
+                  vertex / CLHEP::cm, " cm");
+          }
         }
 
         // is it also in the other volume class (geometrical/physical)?
@@ -531,6 +540,11 @@ bool RMGVertexConfinement::ActualGenerateVertex(G4ThreeVector& vertex) {
           vertex = choice.translation +
                    choice.rotation * RMGGeneratorUtil::rand(choice.sampling_solid, fOnSurface);
           RMGLog::OutDev(RMGLog::debug, "Generated vertex: ", vertex / CLHEP::cm, " cm");
+          if (fForceContainmentCheck && !all_volumes.IsInside(vertex)) {
+            RMGLog::OutDev(RMGLog::error,
+                "Generated vertex not inside sampling volumes (forced containment check): ",
+                vertex / CLHEP::cm, " cm");
+          }
         }
 
         RMGLog::OutDev(RMGLog::debug, "Found good vertex ", vertex / CLHEP::cm, " cm", " after ",
@@ -647,6 +661,15 @@ void RMGVertexConfinement::DefineCommands() {
       .SetStates(G4State_PreInit, G4State_Idle)
       .SetToBeBroadcasted(true);
 
+  fMessengers.back()
+      ->DeclareProperty("ForceContainmentCheck", fForceContainmentCheck)
+      .SetGuidance("If true (or omitted argument), perform a containment check even after sampling "
+                   "from a natively sampleable object. This is only an extra sanity check that does"
+                   "not alter the behaviour.")
+      .SetParameterName("flag", true)
+      .SetStates(G4State_PreInit, G4State_Idle)
+      .SetToBeBroadcasted(false);
+
   fMessengers.push_back(
       std::make_unique<G4GenericMessenger>(this, "/RMG/Generator/Confinement/Physical/",
           "Commands for setting physical volumes up for primary confinement"));
diff --git a/tests/confinement/macros/complex-volume.mac b/tests/confinement/macros/complex-volume.mac
index e82581bb..13576b2d 100644
--- a/tests/confinement/macros/complex-volume.mac
+++ b/tests/confinement/macros/complex-volume.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 
 /RMG/Generator/Confinement/Physical/AddVolume BoxWithHole
 /RMG/Generator/Confinement/Physical/AddVolume BoxAndOrb
diff --git a/tests/confinement/macros/geometrical-and-physical.mac b/tests/confinement/macros/geometrical-and-physical.mac
index d045936d..81d93b1b 100644
--- a/tests/confinement/macros/geometrical-and-physical.mac
+++ b/tests/confinement/macros/geometrical-and-physical.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 
 /RMG/Generator/Confinement/SamplingMode IntersectPhysicalWithGeometrical
 
diff --git a/tests/confinement/macros/geometrical-or-physical.mac b/tests/confinement/macros/geometrical-or-physical.mac
index 565f7f58..66b4c088 100644
--- a/tests/confinement/macros/geometrical-or-physical.mac
+++ b/tests/confinement/macros/geometrical-or-physical.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 
 # /RMG/Generator/Confinement/SampleOnSurface
 
diff --git a/tests/confinement/macros/geometrical.mac b/tests/confinement/macros/geometrical.mac
index 4ea13589..291d3bc1 100644
--- a/tests/confinement/macros/geometrical.mac
+++ b/tests/confinement/macros/geometrical.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 
 # /RMG/Generator/Confinement/SampleOnSurface
 
diff --git a/tests/confinement/macros/native-surface.mac b/tests/confinement/macros/native-surface.mac
index fba0f4d0..152a21b3 100644
--- a/tests/confinement/macros/native-surface.mac
+++ b/tests/confinement/macros/native-surface.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 /RMG/Generator/Confinement/SampleOnSurface true
 /RMG/Generator/Confinement/Physical/AddVolume Box
 /RMG/Generator/Confinement/Physical/AddVolume Orb
diff --git a/tests/confinement/macros/native-volume.mac b/tests/confinement/macros/native-volume.mac
index 55ca366d..0cce9b7e 100644
--- a/tests/confinement/macros/native-volume.mac
+++ b/tests/confinement/macros/native-volume.mac
@@ -1,6 +1,7 @@
 /control/execute macros/init.mac
 
 /RMG/Generator/Confine Volume
+/RMG/Generator/Confinement/ForceContainmentCheck true
 /RMG/Generator/Confinement/Physical/AddVolume Box
 /RMG/Generator/Confinement/Physical/AddVolume Orb
 /RMG/Generator/Confinement/Physical/AddVolume Sphere