diff --git a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
index 84300d4..4eac201 100644
--- a/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
+++ b/src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java
@@ -97,6 +97,12 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         wasm.write( WASM_BINARY_MAGIC );
         wasm.writeInt32( WASM_BINARY_VERSION );
 
+//        // Section 42, enable GcFeatureOptIn for SpiderMonkey https://github.com/lars-t-hansen/moz-gc-experiments/blob/master/version1.md
+//        wasm.writeVaruint32( 42 );
+//        wasm.writeVaruint32( 1 );
+//        wasm.write( 2 ); // version of GcFeatureOptIn
+//        // End Section 42
+
         writeSection( SectionType.Type, functionTypes );
         writeSection( SectionType.Import, imports.values() );
         writeSection( SectionType.Function, functions.values() );