diff --git a/math/vtk9/files/patch-ThirdParty_diy2_vtkdiy2_include_vtkdiy2_fmt_format.h b/math/vtk9/files/patch-ThirdParty_diy2_vtkdiy2_include_vtkdiy2_fmt_format.h
new file mode 100644
index 000000000000..eb9c13efbe2f
--- /dev/null
+++ b/math/vtk9/files/patch-ThirdParty_diy2_vtkdiy2_include_vtkdiy2_fmt_format.h
@@ -0,0 +1,18 @@
+--- ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/format.h.orig	2023-02-15 04:03:53 UTC
++++ ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/format.h
+@@ -480,6 +480,7 @@ void buffer<T>::append(const U* begin, const U* end) {
+ }
+ }  // namespace internal
+ 
++#ifdef __cpp_char8_t
+ // A UTF-8 string view.
+ class u8string_view : public basic_string_view<char8_t> {
+  public:
+@@ -497,6 +498,7 @@ inline u8string_view operator"" _u(const char* s, std:
+ }
+ }  // namespace literals
+ #endif
++#endif // __cpp_char8_t
+ 
+ // The number of characters to store in the basic_memory_buffer object itself
+ // to avoid dynamic memory allocation.
diff --git a/math/vtk9/files/patch-Utilities_octree_octree_octree__node.txx b/math/vtk9/files/patch-Utilities_octree_octree_octree__node.txx
new file mode 100644
index 000000000000..de91955442bb
--- /dev/null
+++ b/math/vtk9/files/patch-Utilities_octree_octree_octree__node.txx
@@ -0,0 +1,11 @@
+--- Utilities/octree/octree/octree_node.txx.orig	2023-02-15 04:03:53 UTC
++++ Utilities/octree/octree/octree_node.txx
+@@ -207,7 +207,7 @@ const octree_node<T_, d_, A_>& octree_node<T_, d_, A_>
+   {
+     throw std::domain_error("Attempt to access children of an octree leaf node.");
+   }
+-  return this->_M_chilren[child];
++  return this->m_children[child];
+ }
+ 
+ /**\brief Return a reference to a child node.