diff --git a/core/src/main/java/org/synyx/hera/core/MutablePluginRegistry.java b/core/src/main/java/org/synyx/hera/core/MutablePluginRegistry.java
new file mode 100644
index 0000000..77b972c
--- /dev/null
+++ b/core/src/main/java/org/synyx/hera/core/MutablePluginRegistry.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2002-2008 the original author or authors.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package org.synyx.hera.core;
+
+import java.util.List;
+
+
+/**
+ * Extension of {@link PluginRegistry} with additional methods to modify the
+ * registry.
+ * 
+ * @author Oliver Gierke - gierke@synyx.de
+ */
+public interface MutablePluginRegistry<T extends Plugin<S>, S> extends
+        PluginRegistry<T, S> {
+
+    /**
+     * Register plugins.
+     * 
+     * @param plugins the plugins to set
+     */
+    void setPlugins(List<? extends T> plugins);
+
+
+    /**
+     * Adds a given plugin to the registry.
+     * 
+     * @param plugin
+     */
+    void addPlugin(T plugin);
+
+
+    /**
+     * Removes a given plugin from the registry.
+     * 
+     * @param plugin
+     */
+    boolean removePlugin(T plugin);
+}
diff --git a/core/src/main/java/org/synyx/hera/core/PluginRegistry.java b/core/src/main/java/org/synyx/hera/core/PluginRegistry.java
index 73023a7..05e06f1 100644
--- a/core/src/main/java/org/synyx/hera/core/PluginRegistry.java
+++ b/core/src/main/java/org/synyx/hera/core/PluginRegistry.java
@@ -13,30 +13,6 @@ import java.util.List;
  */
 public interface PluginRegistry<T extends Plugin<S>, S> extends Iterable<T> {
 
-    /**
-     * Register plugins.
-     * 
-     * @param plugins the plugins to set
-     */
-    void setPlugins(List<? extends T> plugins);
-
-
-    /**
-     * Adds a given plugin to the registry.
-     * 
-     * @param plugin
-     */
-    void addPlugin(T plugin);
-
-
-    /**
-     * Removes a given plugin from the registry.
-     * 
-     * @param plugin
-     */
-    boolean removePlugin(T plugin);
-
-
     /**
      * Returns the first plugin found for the given originating system. Thus,
      * further configured plugins are ignored.
diff --git a/core/src/main/java/org/synyx/hera/core/SimplePluginRegistry.java b/core/src/main/java/org/synyx/hera/core/SimplePluginRegistry.java
index fcfd5f0..09ec1a3 100644
--- a/core/src/main/java/org/synyx/hera/core/SimplePluginRegistry.java
+++ b/core/src/main/java/org/synyx/hera/core/SimplePluginRegistry.java
@@ -30,7 +30,7 @@ import java.util.List;
  * @author Oliver Gierke - gierke@synyx.de
  */
 public class SimplePluginRegistry<T extends Plugin<S>, S> implements
-        PluginRegistry<T, S> {
+        MutablePluginRegistry<T, S> {
 
     // Registered plugins
     private List<T> plugins;
@@ -78,7 +78,7 @@ public class SimplePluginRegistry<T extends Plugin<S>, S> implements
     /*
      * (non-Javadoc)
      * 
-     * @see org.synyx.hera.core.PluginRegistry#setPlugins(java.util.List)
+     * @see org.synyx.hera.core.MutablePluginRegistry#setPlugins(java.util.List)
      */
     public void setPlugins(List<? extends T> plugins) {
 
@@ -90,7 +90,9 @@ public class SimplePluginRegistry<T extends Plugin<S>, S> implements
     /*
      * (non-Javadoc)
      * 
-     * @see org.synyx.hera.core.PluginRegistry#addPlugin(T)
+     * @see
+     * org.synyx.hera.core.MutablePluginRegistry#addPlugin(org.synyx.hera.core
+     * .Plugin)
      */
     public void addPlugin(T plugin) {
 
@@ -102,8 +104,8 @@ public class SimplePluginRegistry<T extends Plugin<S>, S> implements
      * (non-Javadoc)
      * 
      * @see
-     * org.synyx.hera.core.PluginRegistry#removePlugin(org.synyx.hera.core.Plugin
-     * )
+     * org.synyx.hera.core.MutablePluginRegistry#removePlugin(org.synyx.hera
+     * .core.Plugin)
      */
     public boolean removePlugin(T plugin) {