diff --git a/Modules/Core/Common/include/itkImageRegion.h b/Modules/Core/Common/include/itkImageRegion.h
index add9284c728..8045eb42fc9 100644
--- a/Modules/Core/Common/include/itkImageRegion.h
+++ b/Modules/Core/Common/include/itkImageRegion.h
@@ -275,8 +275,8 @@ class ITK_TEMPLATE_EXPORT ImageRegion final : public Region
   bool
   IsInside(const Self & otherRegion) const
   {
-    const auto otherIndex = otherRegion.m_Index;
-    const auto otherSize = otherRegion.m_Size;
+    const auto & otherIndex = otherRegion.m_Index;
+    const auto & otherSize = otherRegion.m_Size;
 
     for (unsigned int i = 0; i < ImageDimension; ++i)
     {