diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index ad2ad0e87..25a17f42e 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -4,7 +4,7 @@ on:
   push:
     branches: 
       - master
-      - tof_sino_UCL
+      - release_6.3
     paths-ignore:
       - '.appveyor.yml'
       - 'CITATION.cff'
diff --git a/documentation/release_6.3.htm b/documentation/release_6.3.htm
index 98c195595..ff14e76fe 100644
--- a/documentation/release_6.3.htm
+++ b/documentation/release_6.3.htm
@@ -60,6 +60,10 @@ <h2>Patch release info</h2>
         6.3.0 released 31/10/2025<br>
         <a href="https://github.com/UCL/STIR/milestone/12">GitHub Milestone 6.3</a>
       </li>
+      <li>
+        6.3.1 released 26/04/2026<br>
+	Fix a <a href="https://github.com/UCL/STIR/pull/1702">small compilation problem</a>
+      </li>
     </ul>
 
   <h2> Summary for end users (also to be read by developers)</h2>
diff --git a/src/include/stir/IO/GEHDF5Wrapper.h b/src/include/stir/IO/GEHDF5Wrapper.h
index 9d3a8d0e5..4963c02d1 100644
--- a/src/include/stir/IO/GEHDF5Wrapper.h
+++ b/src/include/stir/IO/GEHDF5Wrapper.h
@@ -31,6 +31,7 @@
 #include "H5Cpp.h"
 
 #include <string>
+#include <array>
 
 START_NAMESPACE_STIR