diff -Nru insighttoolkit4-4.13.3withdata-dfsg1/debian/changelog insighttoolkit4-4.13.3withdata-dfsg1/debian/changelog
--- insighttoolkit4-4.13.3withdata-dfsg1/debian/changelog	2020-12-28 19:55:32.000000000 +0000
+++ insighttoolkit4-4.13.3withdata-dfsg1/debian/changelog	2021-05-04 08:51:08.000000000 +0000
@@ -1,3 +1,13 @@
+insighttoolkit4 (4.13.3withdata-dfsg1-4.1) unstable; urgency=medium
+
+  * Non-maintainer upload.
+  * libinsighttoolkit4.13: Add Breaks: libinsighttoolkit4.12 for smoother
+    upgrades from buster. The libraries are not co-installable due to the
+    libhdf5-103 -> libhdf5-103-1 and other package renames.
+    Closes: #986927
+
+ -- Andreas Beckmann <anbe@debian.org>  Tue, 04 May 2021 10:51:08 +0200
+
 insighttoolkit4 (4.13.3withdata-dfsg1-4) unstable; urgency=medium
 
   * Team upload.
diff -Nru insighttoolkit4-4.13.3withdata-dfsg1/debian/control insighttoolkit4-4.13.3withdata-dfsg1/debian/control
--- insighttoolkit4-4.13.3withdata-dfsg1/debian/control	2020-12-28 19:44:45.000000000 +0000
+++ insighttoolkit4-4.13.3withdata-dfsg1/debian/control	2021-04-14 08:02:47.000000000 +0000
@@ -34,6 +34,7 @@
 Section: libs
 Architecture: amd64 i386
 Depends: ${shlibs:Depends}, ${misc:Depends}
+Breaks: libinsighttoolkit4.12
 Description: Image processing toolkit for registration and segmentation - runtime
  ITK is an open-source software toolkit for performing registration and
  segmentation. Segmentation is the process of identifying and