diff --git a/src/de/inetsoftware/jwebassembly/module/ClassFileLoader.java b/src/de/inetsoftware/jwebassembly/module/ClassFileLoader.java
index 822b286..0755ae2 100644
--- a/src/de/inetsoftware/jwebassembly/module/ClassFileLoader.java
+++ b/src/de/inetsoftware/jwebassembly/module/ClassFileLoader.java
@@ -1,5 +1,5 @@
 /*
-   Copyright 2020 - 2022 Volker Berlin (i-net software)
+   Copyright 2020 - 2023 Volker Berlin (i-net software)
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -24,6 +24,7 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 import de.inetsoftware.classparser.ClassFile;
+import de.inetsoftware.jwebassembly.WasmException;
 
 /**
  * Cache and manager for the loaded ClassFiles
@@ -87,6 +88,26 @@ public class ClassFileLoader {
         return classFile;
     }
 
+    /**
+     * Get the ClassFile from cache or load it. This returns ever a ClassFile or throw an exception if not found.
+     * 
+     * @param className
+     *            the class name like "java/lang/Object"
+     * @return the ClassFile or null
+     * @throws IOException
+     *             If any I/O error occur
+     * @throws WasmException
+     *             if the class was not found
+     */
+    @Nonnull
+    public ClassFile getClassFile( String className ) throws IOException, WasmException {
+        ClassFile classFile = get( className );
+        if( classFile != null ) {
+            return classFile;
+        }
+        throw new WasmException( "Missing class: " + className, -1 );
+    }
+
     /**
      * Add a class file to the weak cache.
      * 
diff --git a/src/de/inetsoftware/jwebassembly/module/TypeManager.java b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
index 6c7440a..735999b 100644
--- a/src/de/inetsoftware/jwebassembly/module/TypeManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018 - 2022 Volker Berlin (i-net software)
+   Copyright 2018 - 2023 Volker Berlin (i-net software)
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ -871,7 +871,7 @@ public class TypeManager {
 
             // list classes of the hierarchy and its interfaces
             Set<String> interfaceNames = new LinkedHashSet<>();
-            for( ClassFile classFile = classFileLoader.get( name );; ) {
+            for( ClassFile classFile = classFileLoader.getClassFile( name );; ) {
                 classFiles.add( classFile );
                 listInterfaceTypes( classFile, types, classFileLoader, interfaceTypes, interfaceNames );
 
@@ -879,7 +879,7 @@ public class TypeManager {
                 if( superClass == null ) {
                     break;
                 }
-                classFile = classFileLoader.get( superClass.getName() );
+                classFile = classFileLoader.getClassFile( superClass.getName() );
             }
 
             // if the top most class abstract then there can be no instance. A itable we need only for an instance
@@ -890,7 +890,7 @@ public class TypeManager {
             // create the itables for all interfaces of this type
             for( StructType type : interfaceTypes ) {
                 String interName = type.name;
-                ClassFile interClassFile = classFileLoader.get( interName );
+                ClassFile interClassFile = classFileLoader.getClassFile( interName );
                 List<FunctionName> iMethods = null;
 
                 for( MethodInfo interMethod : interClassFile.getMethods() ) {
@@ -907,7 +907,7 @@ public class TypeManager {
                         if( method == null ) {
                             // search if there is a default implementation in an interface
                             for( String iClassName : interfaceNames ) {
-                                ClassFile iClassFile = classFileLoader.get( iClassName );
+                                ClassFile iClassFile = classFileLoader.getClassFile( iClassName );
                                 method = iClassFile.getMethod( iName.methodName, iName.signature );
                                 if( method != null ) {
                                     break;