diff --git a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/CglibPlugin.java b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/CglibPlugin.java
index 8cee2b9..215fc32 100644
--- a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/CglibPlugin.java
+++ b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/CglibPlugin.java
@@ -32,6 +32,9 @@ public class CglibPlugin implements LoadtimeInstrumentationPlugin {
 
 	// implementing LoadtimeInstrumentationPlugin
 	public boolean accept(String slashedTypeName, ClassLoader classLoader, ProtectionDomain protectionDomain, byte[] bytes) {
+		if (slashedTypeName==null) {
+			return false;
+		}
 		return slashedTypeName.equals("net/sf/cglib/core/AbstractClassGenerator");
 		// || slashedTypeName.equals("net/sf/cglib/reflect/FastClass");
 	}
diff --git a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/GroovyPlugin.java b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/GroovyPlugin.java
index b6b044e..6712ff4 100644
--- a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/GroovyPlugin.java
+++ b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/GroovyPlugin.java
@@ -51,6 +51,9 @@ public class GroovyPlugin implements LoadtimeInstrumentationPlugin, ReloadEventP
 	// implementing LoadtimeInstrumentationPlugin
 	public boolean accept(String slashedTypeName, ClassLoader classLoader, ProtectionDomain protectionDomain, byte[] bytes) {
 		// TODO take classloader into account?
+		if (slashedTypeName==null) {
+			return false;
+		}
 		if (!allowCompilableCallSites) {
 			return slashedTypeName.equals("org/codehaus/groovy/runtime/callsite/GroovySunClassLoader")
 					|| slashedTypeName.equals("org/codehaus/groovy/runtime/callsite/CallSiteGenerator");
diff --git a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/SpringPlugin.java b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/SpringPlugin.java
index 4006f93..19a3dc7 100644
--- a/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/SpringPlugin.java
+++ b/org.springsource.loaded/src/main/java/org/springsource/loaded/agent/SpringPlugin.java
@@ -63,7 +63,9 @@ public class SpringPlugin implements LoadtimeInstrumentationPlugin, ReloadEventP
 
 	public boolean accept(String slashedTypeName, ClassLoader classLoader, ProtectionDomain protectionDomain, byte[] bytes) {
 		// TODO take classloader into account?
-
+		if (slashedTypeName == null) {
+			return false;
+		}
 		// Just interested in whether this type got loaded
 		if (slashedTypeName.equals("org/springframework/beans/CachedIntrospectionResults")) {
 			cachedIntrospectionResultsClassLoaded = true;