diff --git a/common/cpw/mods/fml/relauncher/IFMLLoadingPlugin.java b/common/cpw/mods/fml/relauncher/IFMLLoadingPlugin.java
index 972d9706f1..9349273189 100644
--- a/common/cpw/mods/fml/relauncher/IFMLLoadingPlugin.java
+++ b/common/cpw/mods/fml/relauncher/IFMLLoadingPlugin.java
@@ -1,5 +1,9 @@
 package cpw.mods.fml.relauncher;
 
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.Map;
 
 /**
@@ -52,4 +56,23 @@ public interface IFMLLoadingPlugin
      * "coremodLocation" : the file this coremod loaded from,
      */
     void injectData(Map<String, Object> data);
+
+
+    /**
+     * Annotate your load plugin with a list of package prefixes that will *not* be
+     * processed by the ASM transformation stack.
+     *
+     * Your plugin, and any transformers should *definitely* be in this list, because
+     * otherwise you can face problems with the classloader trying to transform classes
+     * with your transformer, whilst it is *loading* your transformer. Not pretty.
+     *
+     * @author cpw
+     *
+     */
+    @Retention(RetentionPolicy.RUNTIME)
+    @Target(ElementType.TYPE)
+    public @interface TransformerExclusions
+    {
+        public String[] value() default "";
+    }
 }
diff --git a/common/cpw/mods/fml/relauncher/RelaunchClassLoader.java b/common/cpw/mods/fml/relauncher/RelaunchClassLoader.java
index f5c818452c..3e17d947eb 100644
--- a/common/cpw/mods/fml/relauncher/RelaunchClassLoader.java
+++ b/common/cpw/mods/fml/relauncher/RelaunchClassLoader.java
@@ -9,27 +9,28 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.logging.Level;
 
 public class RelaunchClassLoader extends URLClassLoader
 {
-    private static String[] excludedPackages = {
-        "java.", "sun.",
-        "cpw.mods.fml.relauncher.", "net.minecraftforge.classloading."
-    };
+    // Left behind for CCC/NEI compatibility
+    private static String[] excludedPackages = new String[0];
+    // Left behind for CCC/NEI compatibility
+    private static String[] transformerExclusions = new String[0];
 
-    private static String[] transformerExclusions =
-    {
-        "org.objectweb.asm.", "com.google.common.", "cpw.mods.fml.", "javax."
-    };
     private List<URL> sources;
     private ClassLoader parent;
 
     private List<IClassTransformer> transformers;
     private Map<String, Class> cachedClasses;
 
+    private Set<String> classLoaderExceptions = new HashSet<String>();
+    private Set<String> transformerExceptions = new HashSet<String>();
+
     public RelaunchClassLoader(URL[] sources)
     {
         super(sources, null);
@@ -39,6 +40,18 @@ public class RelaunchClassLoader extends URLClassLoader
         this.transformers = new ArrayList<IClassTransformer>(2);
 //        ReflectionHelper.setPrivateValue(ClassLoader.class, null, this, "scl");
         Thread.currentThread().setContextClassLoader(this);
+
+        // standard classloader exclusions
+        addClassLoaderExclusion("java.");
+        addClassLoaderExclusion("sun.");
+        addClassLoaderExclusion("cpw.mods.fml.relauncher.");
+        addClassLoaderExclusion("net.minecraftforge.classloading.");
+
+        // standard transformer exclusions
+        addTransformerExclusion("javax.");
+        addTransformerExclusion("cpw.mods.fml.");
+        addTransformerExclusion("org.objectweb.asm.");
+        addTransformerExclusion("com.google.common.");
     }
 
     public void registerTransformer(String transformerClassName)
@@ -55,7 +68,19 @@ public class RelaunchClassLoader extends URLClassLoader
     @Override
     public Class<?> findClass(String name) throws ClassNotFoundException
     {
-        for (String st : excludedPackages)
+        // NEI/CCC compatibility code
+        if (excludedPackages.length != 0)
+        {
+            classLoaderExceptions.addAll(Arrays.asList(excludedPackages));
+            excludedPackages = new String[0];
+        }
+        if (transformerExclusions.length != 0)
+        {
+            transformerExceptions.addAll(Arrays.asList(transformerExclusions));
+            transformerExclusions = new String[0];
+        }
+
+        for (String st : classLoaderExceptions)
         {
             if (name.startsWith(st))
             {
@@ -68,7 +93,7 @@ public class RelaunchClassLoader extends URLClassLoader
             return cachedClasses.get(name);
         }
 
-        for (String st : transformerExclusions)
+        for (String st : transformerExceptions)
         {
             if (name.startsWith(st))
             {
@@ -181,4 +206,14 @@ public class RelaunchClassLoader extends URLClassLoader
     {
         return Collections.unmodifiableList(transformers);
     }
+
+    private void addClassLoaderExclusion(String toExclude)
+    {
+        classLoaderExceptions.add(toExclude);
+    }
+
+    void addTransformerExclusion(String toExclude)
+    {
+        transformerExceptions.add(toExclude);
+    }
 }
diff --git a/common/cpw/mods/fml/relauncher/RelaunchLibraryManager.java b/common/cpw/mods/fml/relauncher/RelaunchLibraryManager.java
index 7143f86a74..c5bd92a96d 100644
--- a/common/cpw/mods/fml/relauncher/RelaunchLibraryManager.java
+++ b/common/cpw/mods/fml/relauncher/RelaunchLibraryManager.java
@@ -25,6 +25,8 @@ import java.util.jar.Attributes;
 import java.util.jar.JarFile;
 import java.util.logging.Level;
 
+import cpw.mods.fml.relauncher.IFMLLoadingPlugin.TransformerExclusions;
+
 public class RelaunchLibraryManager
 {
     private static String[] rootPlugins =  { "cpw.mods.fml.relauncher.FMLCorePlugin" , "net.minecraftforge.classloading.FMLForgePlugin" };
@@ -319,7 +321,16 @@ public class RelaunchLibraryManager
             try
             {
                 downloadMonitor.updateProgressString("Loading coremod %s", coreMod.getName());
+                classLoader.addTransformerExclusion(fmlCorePlugin);
                 Class<?> coreModClass = Class.forName(fmlCorePlugin, true, classLoader);
+                TransformerExclusions trExclusions = coreModClass.getAnnotation(IFMLLoadingPlugin.TransformerExclusions.class);
+                if (trExclusions!=null)
+                {
+                    for (String st : trExclusions.value())
+                    {
+                        classLoader.addTransformerExclusion(st);
+                    }
+                }
                 IFMLLoadingPlugin plugin = (IFMLLoadingPlugin) coreModClass.newInstance();
                 loadPlugins.add(plugin);
                 pluginLocations .put(plugin, coreMod);