diff --git a/common/cpw/mods/fml/common/asm/transformers/AccessTransformer.java b/common/cpw/mods/fml/common/asm/transformers/AccessTransformer.java
index 65a04619c8..bc1a376eff 100644
--- a/common/cpw/mods/fml/common/asm/transformers/AccessTransformer.java
+++ b/common/cpw/mods/fml/common/asm/transformers/AccessTransformer.java
@@ -145,6 +145,7 @@ public class AccessTransformer implements IClassTransformer
     @Override
     public byte[] transform(String name, byte[] bytes)
     {
+    	if (bytes == null) { return null; }
         if (!modifiers.containsKey(name)) { return bytes; }
 
         ClassNode classNode = new ClassNode();
diff --git a/common/cpw/mods/fml/common/asm/transformers/MarkerTransformer.java b/common/cpw/mods/fml/common/asm/transformers/MarkerTransformer.java
index 6551b03b80..f9a2985a71 100644
--- a/common/cpw/mods/fml/common/asm/transformers/MarkerTransformer.java
+++ b/common/cpw/mods/fml/common/asm/transformers/MarkerTransformer.java
@@ -89,6 +89,7 @@ public class MarkerTransformer implements IClassTransformer
     @Override
     public byte[] transform(String name, byte[] bytes)
     {
+    	if (bytes == null) { return null; }
         if (!markers.containsKey(name)) { return bytes; }
 
         ClassNode classNode = new ClassNode();
diff --git a/common/cpw/mods/fml/common/asm/transformers/SideTransformer.java b/common/cpw/mods/fml/common/asm/transformers/SideTransformer.java
index 27b89c60ad..87716bbd06 100644
--- a/common/cpw/mods/fml/common/asm/transformers/SideTransformer.java
+++ b/common/cpw/mods/fml/common/asm/transformers/SideTransformer.java
@@ -23,6 +23,8 @@ public class SideTransformer implements IClassTransformer
     @Override
     public byte[] transform(String name, byte[] bytes)
     {
+    	if (bytes == null) { return null; }
+
         ClassNode classNode = new ClassNode();
         ClassReader classReader = new ClassReader(bytes);
         classReader.accept(classNode, 0);
@@ -33,7 +35,7 @@ public class SideTransformer implements IClassTransformer
             {
                 System.out.println(String.format("Attempted to load class %s for invalid side %s", classNode.name, SIDE));
             }
-            return null;
+            throw new RuntimeException(String.format("Attempted to load class %s for invalid side %s", classNode.name, SIDE));
         }
 
         Iterator<FieldNode> fields = classNode.fields.iterator();