diff --git a/phpmd.xml b/phpmd.xml
index bc2e6a4..35a8024 100644
--- a/phpmd.xml
+++ b/phpmd.xml
@@ -57,7 +57,32 @@
     <rule ref="rulesets/design.xml/NumberOfChildren"/>
     <rule ref="rulesets/design.xml/DepthOfInheritance"/>
     <rule ref="rulesets/design.xml/CouplingBetweenObjects"/>
-    <rule ref="rulesets/design.xml/DevelopmentCodeFragment"/>
+    <!-- DevelopmentCodeFragment MUST carry ignore-namespaces=true, or it is dead
+         code in this ruleset. See ConductionNL/openregister#2286.
+
+         PDepend resolves an unqualified call inside a namespaced file to the
+         CURRENT-NAMESPACE-qualified image, so `var_dump($x)` in
+         `namespace OCA\MyApp\Service;` reaches the rule as
+         `OCA\MyApp\Service\var_dump`, which never matches the
+         `unwanted-functions` list. All of our production PHP is namespaced, so
+         with the default (false) the rule catches nothing anywhere.
+
+         Measured on phpmd 2.15.0 / PHP 8.3.32: byte-identical probe class,
+         namespaced -> exit 0, non-namespaced -> exit 2. With
+         ignore-namespaces=true the rule strips the enclosing namespace before
+         matching, the namespaced probe is reported (exit 2), and a clean
+         namespaced file stays exit 0.
+
+         Note: hydra gate 2 (forbidden-patterns) independently greps lib/ for
+         var_dump / die / error_log / print_r / dd / dump and is the broader
+         control - it also catches calls outside methods, which this rule (a
+         MethodAware/FunctionAware rule) cannot see. This rule is the
+         `composer check:strict` half of the same guard; keep both. -->
+    <rule ref="rulesets/design.xml/DevelopmentCodeFragment">
+        <properties>
+            <property name="ignore-namespaces" value="true"/>
+        </properties>
+    </rule>
     <rule ref="rulesets/design.xml/EmptyCatchBlock"/>
     <rule ref="rulesets/design.xml/CountInLoopExpression"/>