--- a/js/src/jit/x86-shared/Disassembler-x86-shared.cpp
+++ b/js/src/jit/x86-shared/Disassembler-x86-shared.cpp
@@ -157,17 +157,17 @@ DecodeScale(uint8_t modrm, uint8_t sib, 
 #define PackOpcode(op0, op1, op2) ((op0) | ((op1) << 8) | ((op2) << 16))
 #define Pack2ByteOpcode(op1) PackOpcode(OP_2BYTE_ESCAPE, op1, 0)
 #define Pack3ByteOpcode(op1, op2) PackOpcode(OP_2BYTE_ESCAPE, op1, op2)
 
 uint8_t*
 js::jit::Disassembler::DisassembleHeapAccess(uint8_t* ptr, HeapAccess* access)
 {
     VexOperandType type = VEX_PS;
-    uint32_t opcode = OP_HLT;
+    uint32_t opcode = OP_NOP_00;
     uint8_t modrm = 0;
     uint8_t sib = 0;
     uint8_t rex = 0;
     int32_t disp = 0;
     int32_t imm = 0;
     bool haveImm = false;
     int opsize = 4;