diff --git a/VecGeom/volumes/PlacedAssembly.h b/VecGeom/volumes/PlacedAssembly.h
index 51c67825ed1fc0642aa91837a96e6cb1c5e8f348..89811fa00de66843111c8e9ab9d721e15906882b 100644
--- a/VecGeom/volumes/PlacedAssembly.h
+++ b/VecGeom/volumes/PlacedAssembly.h
@@ -262,6 +262,8 @@ public:
   // if this function returns true it modifies the navigation state to point to the first non-assembly volume
   // the point is contained in
   // this function is not part of the generic UnplacedVolume interface but we could consider doing so
+  // N.B To work correctly, the input state must be initialized to point to the parent volume of this placed assembly
+  //     otherwise the Push/Pop cannot work correctly since they do not match a valid navigation state
   VECCORE_ATT_HOST_DEVICE
   bool Contains(Vector3D<Precision> const &p, Vector3D<Precision> &lp, NavigationState &state) const
   {
diff --git a/test/core/AssemblyTest.cpp b/test/core/AssemblyTest.cpp
index 7780c2e7a1053cf6e2e8f2903e9662e191e1440b..caa55d70dfee44a7efd3e03d20646f171b6a5c5b 100644
--- a/test/core/AssemblyTest.cpp
+++ b/test/core/AssemblyTest.cpp
@@ -54,13 +54,22 @@ int main()
     Vector3D<Precision> p2(20., 0., 0.);
     Vector3D<Precision> lp(0., 0., 0.);
     NavigationState *state = NavigationState::MakeInstance(10);
+    // State must point to assembly parent (none in this case)
+    state->Clear();
     std::cerr << pa->Contains(p, lp, *state) << "\n";
+    state->Clear();
     assert(!pa->Contains(p, lp, *state));
+    state->Clear();
     std::cerr << pa->Contains(p2, lp, *state) << "\n";
+    state->Clear();
     assert(pa->Contains(p2, lp, *state));
+    state->Clear();
     std::cerr << pa->Contains(p) << "\n";
+    state->Clear();
     assert(!pa->Contains(p));
+    state->Clear();
     std::cerr << pa->Contains(p2) << "\n";
+    state->Clear();
     assert(pa->Contains(p2));
 
     assert(pa->SafetyToIn(Vector3D<Precision>(-10, 0, 0)) == 0.);