diff --git a/src/de/inetsoftware/jwebassembly/module/FunctionManager.java b/src/de/inetsoftware/jwebassembly/module/FunctionManager.java
index d6aaa0e..daeed10 100644
--- a/src/de/inetsoftware/jwebassembly/module/FunctionManager.java
+++ b/src/de/inetsoftware/jwebassembly/module/FunctionManager.java
@@ -119,7 +119,12 @@ class FunctionManager {
      */
     void markAsScanned( FunctionName name, boolean needThisParameter ) {
         FunctionState state = getOrCreate( name );
-        state.state = State.Scanned;
+        switch( state.state ) {
+            case None:
+            case Needed:
+                state.state = State.Scanned;
+                break;
+        }
         state.needThisParameter = needThisParameter;
     }
 
@@ -133,6 +138,16 @@ class FunctionManager {
         getOrCreate( name ).state = State.Written;
     }
 
+    /**
+     * Mark the a function as abstract or interface. This function can be called but will not be write to the wasm file.
+     * 
+     * @param name
+     *            the function name
+     */
+    void markAsAbstract( FunctionName name ) {
+        getOrCreate( name ).state = State.Abstract;
+    }
+
     /**
      * Same like markAsNeeded but it will replace the function name if already registered.
      * 
@@ -230,14 +245,13 @@ class FunctionManager {
     }
 
     /**
-     * Get all FunctionNames that need imported
+     * Get all FunctionNames that are abstract and used.
      * 
      * @return an iterator
      */
-    Iterator<FunctionName> getNeededFunctions() {
+    Iterator<FunctionName> getAbstractedFunctions() {
         return iterator( entry -> {
-            FunctionState state = entry.getValue();
-            switch( state.state ) {
+            switch( entry.getValue().state ) {
                 case Needed:
                 case Scanned:
                     return true;
@@ -386,6 +400,6 @@ class FunctionManager {
     }
 
     private static enum State {
-        None, Needed, Scanned, Written;
+        None, Needed, Scanned, Written, Abstract;
     }
 }
diff --git a/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java b/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
index 458e48d..80c8afa 100644
--- a/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
+++ b/src/de/inetsoftware/jwebassembly/module/ModuleGenerator.java
@@ -299,11 +299,17 @@ public class ModuleGenerator {
         }
 
         // init/write the function types
-        for( Iterator<FunctionName> iterator = functions.getNeededFunctions(); iterator.hasNext(); ) {
+        for( Iterator<FunctionName> iterator = functions.getWriteLater(); iterator.hasNext(); ) {
             FunctionName name = iterator.next();
             writeMethodSignature( name, null );
         }
 
+        // register types of abstract and interface methods
+        for( Iterator<FunctionName> iterator = functions.getAbstractedFunctions(); iterator.hasNext(); ) {
+            FunctionName name = iterator.next();
+            //writeMethodSignature( name, null );
+        }
+
         JWebAssembly.LOGGER.fine( "scan finsih" );
         types.prepareFinish( writer, classFileLoader );
         functions.prepareFinish();
@@ -478,6 +484,9 @@ public class ModuleGenerator {
             } else if( code != null ) { // abstract methods and interface methods does not have code
                 javaCodeBuilder.buildCode( code, method );
                 return javaCodeBuilder;
+            } else if( method.isAbstract() ) {
+                functions.markAsAbstract( new FunctionName( method ) ); // there is nothing to write for an abstract method
+                return null;
             } else {
                 FunctionName name = new FunctionName( method );
                 if( "java/lang/Class.typeTableMemoryOffset()I".equals( name.signatureName ) ) {