diff --git a/guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AbstractUserGroup.java b/guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AbstractUserGroup.java
index f63bfae7f..2c89cb050 100644
--- a/guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AbstractUserGroup.java
+++ b/guacamole-ext/src/main/java/org/apache/guacamole/net/auth/AbstractUserGroup.java
@@ -29,7 +29,7 @@ import org.apache.guacamole.net.auth.permission.SystemPermissionSet;
  * Base implementation of UserGroup which provides default implementations of
  * most functions.
  */
-public class AbstractUserGroup extends AbstractIdentifiable implements UserGroup {
+public abstract class AbstractUserGroup extends AbstractIdentifiable implements UserGroup {
 
     /**
      * {@inheritDoc}