diff --git a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
index b694c1c..a5490c3 100644
--- a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
@@ -1395,7 +1395,7 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
                 break;
             case NULL:
                 opCode = REF_NULL;
-                type = options.useGC() ? ValueType.eqref : ValueType.externref;
+                type = options.useGC() ? type : ValueType.externref;
                 break;
             default:
                 throw new Error( "Unknown operator: " + op );
diff --git a/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java b/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
index 5ccd80a..8106a40 100644
--- a/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
+++ b/src/de/inetsoftware/jwebassembly/binary/WasmOutputStream.java
@@ -98,8 +98,7 @@ class WasmOutputStream extends LittleEndianOutputStream {
     public void writeRefValueType( AnyType type ) throws IOException {
         if( type.isRefType() ) {
             if( options.useGC() ) {
-                //TODO writeValueType( ValueType.ref_type );
-                type = ValueType.eqref;
+                writeValueType( ValueType.optref );
             } else {
                 type = ValueType.externref;
             }
diff --git a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
index c82f2ce..c721505 100644
--- a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
@@ -108,7 +108,7 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
                     case 0: // nop
                         break;
                     case 1: // aconst_null
-                        addStructInstruction( StructOperator.NULL, null, null, codePos, lineNumber );
+                        addStructInstruction( StructOperator.NULL, "java/lang/Object", null, codePos, lineNumber );
                         break;
                     case 2: // iconst_m1
                     case 3: // iconst_0
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmStructInstruction.java b/src/de/inetsoftware/jwebassembly/module/WasmStructInstruction.java
index 487dcb9..905c7c7 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmStructInstruction.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmStructInstruction.java
@@ -64,10 +64,10 @@ class WasmStructInstruction extends WasmInstruction {
      * @param types
      *            the type manager
      */
-    WasmStructInstruction( @Nullable StructOperator op, @Nullable String typeName, @Nullable NamedStorageType fieldName, int javaCodePos, int lineNumber, TypeManager types ) {
+    WasmStructInstruction( @Nullable StructOperator op, @Nonnull String typeName, @Nullable NamedStorageType fieldName, int javaCodePos, int lineNumber, TypeManager types ) {
         super( javaCodePos, lineNumber );
         this.op = op;
-        this.type = typeName == null ? null : types.valueOf( typeName );
+        this.type = types.valueOf( typeName );
         this.fieldName = fieldName;
         if( type != null && fieldName != null ) {
             type.useFieldName( fieldName );
diff --git a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
index 80d8d53..cc21ef3 100644
--- a/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/text/TextModuleWriter.java
@@ -861,8 +861,12 @@ public class TextModuleWriter extends ModuleWriter {
                 operation = "struct.set";
                 break;
             case NULL:
-                operation = options.useGC() ? "ref.null eq" : "ref.null extern";
-                type = null;
+                if( options.useGC() ) {
+                    operation = "ref.null";
+                } else {
+                    operation = "ref.null extern";
+                    type = null;
+                }
                 break;
             default:
                 throw new Error( "Unknown operator: " + op );