diff --git a/diylc/diylc-core/pom.xml b/diylc/diylc-core/pom.xml
index dbd8a570..4fde8d0e 100644
--- a/diylc/diylc-core/pom.xml
+++ b/diylc/diylc-core/pom.xml
@@ -74,6 +74,17 @@
             <version>5.11.0</version>
             <scope>test</scope>
         </dependency>
+        <!-- Subclass mock maker, selected in src/test/resources/mockito-extensions. Mockito 5
+             defaults to the inline maker, which attaches a Java agent to the running JVM; that
+             attachment fails outright on some CI JDKs and is deprecated since Java 21. Every type
+             mocked in these tests is an interface, which the subclass maker handles without an
+             agent. -->
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-subclass</artifactId>
+            <version>5.11.0</version>
+            <scope>test</scope>
+        </dependency>
         
         <!-- Local dependencies from lib folder -->
         <dependency>
diff --git a/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MemberAccessor b/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MemberAccessor
new file mode 100644
index 00000000..71111e33
--- /dev/null
+++ b/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MemberAccessor
@@ -0,0 +1 @@
+member-accessor-reflection
diff --git a/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker b/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
new file mode 100644
index 00000000..fdbd0b15
--- /dev/null
+++ b/diylc/diylc-core/src/test/resources/mockito-extensions/org.mockito.plugins.MockMaker
@@ -0,0 +1 @@
+mock-maker-subclass