diff --git a/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java b/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
index 2baf348..fc05c78 100644
--- a/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
+++ b/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
@@ -473,7 +473,7 @@ public class ModuleGenerator {
                 return javaCodeBuilder;
             } else {
                 FunctionName name = new FunctionName( method );
-                if( "de/inetsoftware/jwebassembly/module/ReplacementForClass.typeTableMemoryOffset()I".equals( name.signatureName ) ) {
+                if( "java/lang/Class.typeTableMemoryOffset()I".equals( name.signatureName ) ) {
                     return types.getTypeTableMemoryOffsetFunctionName().getCodeBuilder( watParser );
                 }
                 throw new WasmException( "Abstract or native method can not be used: " + name.signatureName, -1 );
diff --git a/src/de/inetsoftware/jwebassembly/module/ReplacementForClass.java b/src/de/inetsoftware/jwebassembly/module/ReplacementForClass.java
index acec700..750652d 100644
--- a/src/de/inetsoftware/jwebassembly/module/ReplacementForClass.java
+++ b/src/de/inetsoftware/jwebassembly/module/ReplacementForClass.java
@@ -57,7 +57,14 @@ class ReplacementForClass {
      */
     @WasmTextCode( "local.get 0 " // THIS
                     + "struct.get java/lang/Object .vtable " // vtable is on index 0
-                    + "call $de/inetsoftware/jwebassembly/module/ReplacementForClass.classConstant(I)Lde/inetsoftware/jwebassembly/module/ReplacementForClass; " //
+                    + "local.tee 1 " // save the vtable location
+                    + "i32.const " + TypeManager.TYPE_DESCRIPTION_INSTANCEOF_OFFSET + " " // vtable is on index 0
+                    + "i32.add " //
+                    + "call $java/lang/Class.getIntFromMemory(I)I " //
+                    + "local.get 1 " // get the vtable location
+                    + "i32.add " //
+                    + "call $java/lang/Class.getIntFromMemory(I)I " //
+                    + "call $java/lang/Class.classConstant(I)Lde/inetsoftware/jwebassembly/module/ReplacementForClass; " //
                     + "return " //
     )
     @Replace( "java/lang/Object.getClass()Ljava/lang/Class;" )
@@ -122,7 +129,7 @@ class ReplacementForClass {
      */
     @WasmTextCode( "local.get 0 " + //
                     "local.get 1 " + //
-                    "table.set 2 " + //
+                    "table.set 2 " + // table 2 is used for classes
                     "return" )
     private static native void setClassIntoTable( int strIdx, ReplacementForClass clazz );
 
diff --git a/src/de/inetsoftware/jwebassembly/module/TypeManager.java b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
index 78f04af..3e2d083 100644
--- a/src/de/inetsoftware/jwebassembly/module/TypeManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
@@ -127,10 +127,11 @@ public class TypeManager {
         }
 
         // write type table
-        ByteArrayOutputStream dataStream = writer.dataStream;
-        typeTableOffset = dataStream.size();
+        @SuppressWarnings( "resource" )
+        LittleEndianOutputStream dataStream = new LittleEndianOutputStream( writer.dataStream );
+        typeTableOffset = writer.dataStream.size();
         for( StructType type : structTypes.values() ) {
-            dataStream.write( type.vtableOffset );
+            dataStream.writeInt32( type.vtableOffset );
         }
     }
 
@@ -141,7 +142,7 @@ public class TypeManager {
      */
     WatCodeSyntheticFunctionName getTypeTableMemoryOffsetFunctionName() {
         WatCodeSyntheticFunctionName offsetFunction =
-                        new WatCodeSyntheticFunctionName( "de/inetsoftware/jwebassembly/module/ReplacementForClass", "typeTableMemoryOffset", "()I", "", null, ValueType.i32 ) {
+                        new WatCodeSyntheticFunctionName( "java/lang/Class", "typeTableMemoryOffset", "()I", "", null, ValueType.i32 ) {
                             protected String getCode() {
                                 return "i32.const " + typeTableOffset;
                             }
@@ -219,7 +220,7 @@ public class TypeManager {
                         "instanceof", "local.get 0 " // THIS
                                         + "struct.get java/lang/Object .vtable " // vtable is on index 0
                                         + "local.tee 2 " // save the vtable location
-                                        + "i32.load offset=4 align=4 " // get offset of instanceof inside vtable (int position 1, byte position 4)
+                                        + "i32.load offset=" + TYPE_DESCRIPTION_INSTANCEOF_OFFSET + " align=4 " // get offset of instanceof inside vtable (int position 1, byte position 4)
                                         + "local.get 2 " // get the vtable location
                                         + "i32.add " //
                                         + "local.tee 2 " // save the instanceof location