1 files changed, 14 insertions, 0 deletions
diff --git a/src/wasm-binary.h b/src/wasm-binary.h
index 081924ba0..2ce460c6f 100644
--- a/src/wasm-binary.h
+++ b/src/wasm-binary.h
@@ -386,6 +386,7 @@ public:
   }
 
   void write() {
+    writeHeader();
     writeStart();
     writeMemory();
     writeSignatures();
@@ -396,6 +397,12 @@ public:
     finishUp();
   }
 
+  void writeHeader() {
+    if (debug) std::cerr << "== writeStart" << std::endl;
+    o << int32_t(0x6d736100); // magic number \0asm
+    o << int32_t(10);         // version number
+  }
+
   void writeStart() {
     if (!wasm->start.is()) return;
     if (debug) std::cerr << "== writeStart" << std::endl;
@@ -966,6 +973,8 @@ public:
   WasmBinaryBuilder(AllocatingModule& wasm, std::vector<char>& input, bool debug) : wasm(wasm), allocator(wasm.allocator), input(input), debug(debug), pos(0) {}
 
   void read() {
+    readHeader();
+
     // read sections until the end
     while (1) {
       int8_t section = getInt8();
@@ -1085,6 +1094,11 @@ public:
     pos--;
   }
 
+  void readHeader() {
+    verifyInt32(0x6d736100);
+    verifyInt32(10);
+  }
+
   void readStart() {
     if (debug) std::cerr << "== readStart" << std::endl;
     wasm.start = getString();