diff --git a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
index 706c2ef..eb9948c 100644
--- a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
@@ -467,6 +467,9 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         localsStream.writeVaruint32( locals.size() );
         for( AnyType valueType : locals ) {
             localsStream.writeVaruint32( 1 ); // TODO optimize, write the count of same types.
+            if( valueType.getCode() >= 0 ) {
+                localsStream.writeValueType( ValueType.ref_type );
+            }
             localsStream.writeValueType( valueType );
         }
         WasmOutputStream functionsStream = function.functionsStream = new WasmOutputStream();
diff --git a/src/de/inetsoftware/jwebassembly/binary/StructTypeEntry.java b/src/de/inetsoftware/jwebassembly/binary/StructTypeEntry.java
index a2ef514..bccbda3 100644
--- a/src/de/inetsoftware/jwebassembly/binary/StructTypeEntry.java
+++ b/src/de/inetsoftware/jwebassembly/binary/StructTypeEntry.java
@@ -60,7 +60,7 @@ class StructTypeEntry extends TypeEntry {
         for( NamedStorageType field : this.fields ) {
             stream.writeVarint( 1 ); // 0 - immutable; 1 - mutable 
             if( field.type.getCode() > 0  ) {
-                stream.writeVaruint32( 0x6E );
+                stream.writeValueType( ValueType.ref_type );
             }
             stream.writeValueType( field.type );
         }
diff --git a/src/de/inetsoftware/jwebassembly/wasm/ValueType.java b/src/de/inetsoftware/jwebassembly/wasm/ValueType.java
index 91b4126..4571762 100644
--- a/src/de/inetsoftware/jwebassembly/wasm/ValueType.java
+++ b/src/de/inetsoftware/jwebassembly/wasm/ValueType.java
@@ -27,6 +27,7 @@ public enum ValueType implements AnyType {
     i16(-0x06), //TODO dummy value for https://github.com/WebAssembly/gc
     anyfunc(-0x10),
     anyref(-0x11),
+    ref_type(-0x12 ), // 0x6E https://github.com/lars-t-hansen/moz-gc-experiments/blob/master/version2.md
     except_ref(-0x18), // https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md
     func(-0x20),
     struct(-0x30),