diff --git a/.mvn/extensions.xml b/.mvn/extensions.xml
index 6787906..5f21f2d 100644
--- a/.mvn/extensions.xml
+++ b/.mvn/extensions.xml
@@ -1,5 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<extensions>
+<!-- The xmlns is load-bearing: Renovate's maven manager skips an extensions.xml
+     without a recognised EXTENSIONS namespace, so without it Nisse is never
+     updated. -->
+<extensions xmlns="http://maven.apache.org/EXTENSIONS/1.0.0"
+            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+            xsi:schemaLocation="http://maven.apache.org/EXTENSIONS/1.0.0 https://maven.apache.org/xsd/core-extensions-1.0.0.xsd">
     <!-- Derives ${nisse.jgit.dynamicVersion} from git state, so the tag is the
          only version. See RELEASING.md in reqstool/.github. -->
     <extension>