diff --git a/Modules/Core/Common/include/itkPointSet.h b/Modules/Core/Common/include/itkPointSet.h
index 9b8f6d75e94..aeb3db8defe 100644
--- a/Modules/Core/Common/include/itkPointSet.h
+++ b/Modules/Core/Common/include/itkPointSet.h
@@ -164,7 +164,8 @@ class ITK_TEMPLATE_EXPORT PointSet : public DataObject
   void
   SetPoints(PointsContainer *);
 
-  /** Set the points container using a 1D vector. */
+  /** Set the points container using a 1D vector.
+  \warning This member function is unsafe. It may just work, but it may also lead to undefined behavior. */
   void
   SetPoints(PointsVectorContainer *);
 
diff --git a/Modules/Core/Common/include/itkPointSet.hxx b/Modules/Core/Common/include/itkPointSet.hxx
index 0aed6b93cae..f4731b7d441 100644
--- a/Modules/Core/Common/include/itkPointSet.hxx
+++ b/Modules/Core/Common/include/itkPointSet.hxx
@@ -73,6 +73,8 @@ PointSet<TPixelType, VDimension, TMeshTraits>::SetPoints(PointsVectorContainer *
   {
     itkExceptionMacro("Number of entries in given 1d array incompatible with the point dimension");
   }
+
+  // Note: this cast is unsafe. It may lead to undefined behavior.
   auto * pointsPtr = reinterpret_cast<PointsContainer *>(points);
 
   m_PointsContainer = pointsPtr;