diff -Nru vtk7-7.1.1+dfsg2/debian/changelog vtk7-7.1.1+dfsg2/debian/changelog
--- vtk7-7.1.1+dfsg2/debian/changelog	2021-03-03 20:36:23.000000000 +0000
+++ vtk7-7.1.1+dfsg2/debian/changelog	2021-12-16 16:51:23.000000000 +0000
@@ -1,3 +1,9 @@
+vtk7 (7.1.1+dfsg2-10+rpi1) bookworm-staging; urgency=medium
+
+  * Apply patch from Steve Langasek to fix build with gcc-11.
+
+ -- Peter Michael Green <plugwash@raspbian.org>  Thu, 16 Dec 2021 16:51:23 +0000
+
 vtk7 (7.1.1+dfsg2-10) unstable; urgency=medium
 
   * Team Upload
diff -Nru vtk7-7.1.1+dfsg2/debian/patches/gcc-11.patch vtk7-7.1.1+dfsg2/debian/patches/gcc-11.patch
--- vtk7-7.1.1+dfsg2/debian/patches/gcc-11.patch	1970-01-01 00:00:00.000000000 +0000
+++ vtk7-7.1.1+dfsg2/debian/patches/gcc-11.patch	2021-12-16 16:50:58.000000000 +0000
@@ -0,0 +1,53 @@
+Description: gcc-11 compatibility
+Author: Steve Langasek <steve.langasek@ubuntu.com>
+Bug-Debian: https://bugs.debian.org/984401
+Last-Update: 2021-11-18
+
+Index: vtk7-7.1.1+dfsg2/ThirdParty/xdmf2/vtkxdmf2/libsrc/XdmfDsmComm.cxx
+===================================================================
+--- vtk7-7.1.1+dfsg2.orig/ThirdParty/xdmf2/vtkxdmf2/libsrc/XdmfDsmComm.cxx
++++ vtk7-7.1.1+dfsg2/ThirdParty/xdmf2/vtkxdmf2/libsrc/XdmfDsmComm.cxx
+@@ -52,7 +52,7 @@
+         XdmfErrorMessage("Cannot Receive Message of Length = " << Msg->Length);
+         return(XDMF_FAIL);
+     }
+-    if(Msg->Data <= 0 ){
++    if(!Msg->Data){
+         XdmfErrorMessage("Cannot Receive Message into Data Buffer = " << Msg->Length);
+         return(XDMF_FAIL);
+     }
+@@ -66,7 +66,7 @@
+         XdmfErrorMessage("Cannot Send Message of Length = " << Msg->Length);
+         return(XDMF_FAIL);
+     }
+-    if(Msg->Data <= 0 ){
++    if(!Msg->Data){
+         XdmfErrorMessage("Cannot Send Message from Data Buffer = " << Msg->Length);
+         return(XDMF_FAIL);
+     }
+Index: vtk7-7.1.1+dfsg2/Rendering/Label/vtkLabelHierarchyPrivate.h
+===================================================================
+--- vtk7-7.1.1+dfsg2.orig/Rendering/Label/vtkLabelHierarchyPrivate.h
++++ vtk7-7.1.1+dfsg2/Rendering/Label/vtkLabelHierarchyPrivate.h
+@@ -66,7 +66,7 @@
+     {
+     }
+ 
+-    bool operator () ( const vtkIdType& a, const vtkIdType& b )
++    bool operator () ( const vtkIdType& a, const vtkIdType& b ) const
+     {
+       if (0 == this->Hierarchy)
+       {
+Index: vtk7-7.1.1+dfsg2/Rendering/Label/vtkLabelHierarchy.cxx
+===================================================================
+--- vtk7-7.1.1+dfsg2.orig/Rendering/Label/vtkLabelHierarchy.cxx
++++ vtk7-7.1.1+dfsg2/Rendering/Label/vtkLabelHierarchy.cxx
+@@ -525,7 +525,7 @@
+   {
+   public:
+     bool operator()(const vtkHierarchyNode & a,
+-                    const vtkHierarchyNode & b)
++                    const vtkHierarchyNode & b) const
+     {
+       if (a.Level != b.Level)
+       {
diff -Nru vtk7-7.1.1+dfsg2/debian/patches/series vtk7-7.1.1+dfsg2/debian/patches/series
--- vtk7-7.1.1+dfsg2/debian/patches/series	2020-12-15 19:51:51.000000000 +0000
+++ vtk7-7.1.1+dfsg2/debian/patches/series	2021-12-16 16:50:58.000000000 +0000
@@ -23,3 +23,4 @@
 mysq8_my_bool.patch
 3edc0de2b04ae1e100c229e592d6b9fa94f2915a.patch
 581d9eb874b2b80a3fb21c739a96fa6f955ffb5e.patch
+gcc-11.patch