diff --git a/compiler/utils/x86/assembler_x86.h b/compiler/utils/x86/assembler_x86.h
index bdf8843..46630e3 100644
--- a/compiler/utils/x86/assembler_x86.h
+++ b/compiler/utils/x86/assembler_x86.h
@@ -457,6 +457,7 @@
 
   X86Assembler* lock();
   void cmpxchgl(const Address& address, Register reg);
+  void cmpxchg8b(const Address& address);
 
   void mfence();
 
@@ -476,6 +477,10 @@
     lock()->cmpxchgl(address, reg);
   }
 
+  void LockCmpxchg8b(const Address& address) {
+    lock()->cmpxchg8b(address);
+  }
+
   //
   // Misc. functionality
   //