diff --git a/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java b/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
index c245431..6332a93 100644
--- a/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
+++ b/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
@@ -121,7 +121,7 @@ class WasmOutputStream extends FilterOutputStream {
      *             if an I/O error occurs.
      */
     public void writeDefaultValue( AnyType type ) throws IOException {
-        if( type.getCode() < 0 ) {
+        if( type instanceof ValueType ) {
             ValueType valueType = (ValueType)type;
             switch( valueType ) {
                 case i32:
diff --git a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
index c352c74..52f30a4 100644
--- a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
@@ -479,7 +479,7 @@ public class TextModuleWriter extends ModuleWriter {
      *             if an I/O error occurs.
      */
     private static void writeDefaultValue( Appendable output, AnyType type ) throws IOException {
-        if( type.getCode() < 0 ) {
+        if( type instanceof ValueType ) {
             ValueType valueType = (ValueType)type;
             switch( valueType ) {
                 case i32: