diff --git a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
index 38e8a19..bb71820 100644
--- a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
@@ -33,6 +33,7 @@ import de.inetsoftware.jwebassembly.WasmException;
 import de.inetsoftware.jwebassembly.module.FunctionName;
 import de.inetsoftware.jwebassembly.module.ModuleWriter;
 import de.inetsoftware.jwebassembly.module.TypeManager.StructType;
+import de.inetsoftware.jwebassembly.module.TypeManager.StructTypeKind;
 import de.inetsoftware.jwebassembly.module.ValueTypeConvertion;
 import de.inetsoftware.jwebassembly.module.WasmOptions;
 import de.inetsoftware.jwebassembly.module.WasmTarget;
@@ -497,6 +498,10 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
     protected int writeStructType( StructType type ) throws IOException {
         type.writeToStream( dataStream, (funcName) -> getFunction( funcName ).id, options );
 
+        if( type.getKind() == StructTypeKind.primitive ) {
+            return -9; // Should never use
+        }
+
         if( !options.useGC() ) {
             return ValueType.externref.getCode();
         }
diff --git a/src/de/inetsoftware/jwebassembly/module/TypeManager.java b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
index e55e960..77a388b 100644
--- a/src/de/inetsoftware/jwebassembly/module/TypeManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/TypeManager.java
@@ -148,6 +148,8 @@ public class TypeManager {
 
     private Map<Object, StructType> structTypes = new LinkedHashMap<>();
 
+    private int                     typeIndexCounter;
+
     private boolean                 isFinish;
 
     final WasmOptions               options;
@@ -260,7 +262,7 @@ public class TypeManager {
 
         if( structTypes.size() == 0 ) {
             for( String primitiveTypeName : PRIMITIVE_CLASSES ) {
-                structTypes.put( primitiveTypeName, new StructType( primitiveTypeName, structTypes.size() ) );
+                structTypes.put( primitiveTypeName, new StructType( primitiveTypeName, StructTypeKind.primitive, this ) );
             }
         }
     }
@@ -279,7 +281,12 @@ public class TypeManager {
                 return (StructType)new ValueTypeParser( name, options.types ).next();
             } else {
                 checkStructTypesState( name );
-                type = new StructType( name, structTypes.size() );
+                type = new StructType( name, StructTypeKind.normal, this );
+
+                if( "java/lang/String".equals( name ) ) {
+                    // looks like strings are used, that register helper functions
+                    options.strings.getStringConstantFunction();
+                }
             }
 
             structTypes.put( name, type );
@@ -337,7 +344,7 @@ public class TypeManager {
                 componentClassIndex = ((StructType)arrayType).classIndex;
             }
 
-            type = new ArrayType( arrayType, structTypes.size(), componentClassIndex );
+            type = new ArrayType( arrayType, this, componentClassIndex );
             structTypes.put( arrayType, type );
         }
         return type;
@@ -486,6 +493,15 @@ public class TypeManager {
                         , valueOf( "java/lang/Object" ), ValueType.i32, null, valueOf( "java/lang/Object" ) );
     }
 
+    /**
+     * The kind of type
+     * 
+     * @author Volker Berlin
+     */
+    public static enum StructTypeKind {
+        primitive, normal, array, array_native;
+    }
+
     /**
      * A reference to a type.
      * 
@@ -495,6 +511,8 @@ public class TypeManager {
 
         private final String           name;
 
+        private final StructTypeKind  kind;
+
         private final int              classIndex;
 
         private int                    code = Integer.MAX_VALUE;
@@ -519,12 +537,21 @@ public class TypeManager {
          * 
          * @param name
          *            the Java class name
-         * @param classIndex
-         *            the running index of the class/type
+         * @param kind
+         *            the type kind
+         * @param manager
+         *            the manager which hold all StructTypes
          */
-        protected StructType( String name, int classIndex ) {
+        protected StructType( @Nonnull String name, @Nonnull StructTypeKind kind, @Nonnull TypeManager manager ) {
             this.name = name;
-            this.classIndex = classIndex;
+            this.kind = kind;
+            switch( kind ) {
+                case array_native:
+                    this.classIndex = -1;
+                    break;
+                default:
+                    this.classIndex = manager.typeIndexCounter++;
+            }
         }
 
         /**
@@ -850,6 +877,14 @@ public class TypeManager {
             return type == this || type == ValueType.externref || type == ValueType.anyref || type == ValueType.eqref;
         }
 
+        /**
+         * Get kind of the StructType
+         * @return the type kind
+         */
+        public StructTypeKind getKind() {
+            return kind;
+        }
+
         /**
          * Get the name of the Java type
          * @return the name
diff --git a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
index 477df19..c7afbf7 100644
--- a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
@@ -32,6 +32,7 @@ import de.inetsoftware.jwebassembly.WasmException;
 import de.inetsoftware.jwebassembly.module.FunctionName;
 import de.inetsoftware.jwebassembly.module.ModuleWriter;
 import de.inetsoftware.jwebassembly.module.TypeManager.StructType;
+import de.inetsoftware.jwebassembly.module.TypeManager.StructTypeKind;
 import de.inetsoftware.jwebassembly.module.ValueTypeConvertion;
 import de.inetsoftware.jwebassembly.module.WasmOptions;
 import de.inetsoftware.jwebassembly.module.WasmTarget;
@@ -194,6 +195,10 @@ public class TextModuleWriter extends ModuleWriter {
     protected int writeStructType( StructType type ) throws IOException {
         type.writeToStream( dataStream, (funcName) -> getFunction( funcName ).id, options );
 
+        if( type.getKind() == StructTypeKind.primitive ) {
+            return -9; // Should never use
+        }
+
         if( !options.useGC() ) {
             return ValueType.externref.getCode();
         }
diff --git a/src/de/inetsoftware/jwebassembly/wasm/ArrayType.java b/src/de/inetsoftware/jwebassembly/wasm/ArrayType.java
index cdd6ef9..02af1d4 100644
--- a/src/de/inetsoftware/jwebassembly/wasm/ArrayType.java
+++ b/src/de/inetsoftware/jwebassembly/wasm/ArrayType.java
@@ -15,8 +15,12 @@
  */
 package de.inetsoftware.jwebassembly.wasm;
 
+import javax.annotation.Nonnull;
+
 import de.inetsoftware.jwebassembly.WasmException;
+import de.inetsoftware.jwebassembly.module.TypeManager;
 import de.inetsoftware.jwebassembly.module.TypeManager.StructType;
+import de.inetsoftware.jwebassembly.module.TypeManager.StructTypeKind;
 
 /**
  * A reference to an array type
@@ -35,13 +39,13 @@ public class ArrayType extends StructType {
      * 
      * @param arrayType
      *            the type of the array
-     * @param classIndex
-     *            the running index of the main class/type
+     * @param manager
+     *            the manager which hold all StructTypes
      * @param componentClassIndex
      *            the running index of the component/array class/type
      */
-    public ArrayType( AnyType arrayType, int classIndex, int componentClassIndex ) {
-        super( getJavaClassName( arrayType ), classIndex );
+    public ArrayType( AnyType arrayType, @Nonnull TypeManager manager, int componentClassIndex ) {
+        super( getJavaClassName( arrayType ), StructTypeKind.array, manager );
         this.arrayType = arrayType;
         this.componentClassIndex = componentClassIndex;
     }