diff --git a/doc/appendix-release-notes.xml b/doc/appendix-release-notes.xml
index 168add5c..df3c9b8f 100644
--- a/doc/appendix-release-notes.xml
+++ b/doc/appendix-release-notes.xml
@@ -17,7 +17,7 @@
 
 <!-- remember to update the release date in ../repmgr_version.h.in -->
 
-  <sect1 id="release-5.1-0">
+  <sect1 id="release-5.1.0">
     <title>Release 5.1.0</title>
     <para><emphasis>Mon 13 April, 2020</emphasis></para>