diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 2913274..a975dca 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -460,6 +460,14 @@
   // Always use unsigned comparisons: above and below, not less and greater.
   void CmpInstanceType(Register map, InstanceType type);
 
+  // Check if the map of an object is equal to a specified map and
+  // branch to label if not. Skip the smi check if not required
+  // (object is known to be a heap object)
+  void CheckMap(Register obj,
+                Handle<Map> map,
+                Label* fail,
+                bool is_heap_object);
+
   // Check if the object in register heap_object is a string. Afterwards the
   // register map contains the object map and the register instance_type
   // contains the instance_type. The registers map and instance_type can be the
@@ -712,8 +720,8 @@
   List<Unresolved> unresolved_;
   bool generating_stub_;
   bool allow_stub_calls_;
-  Handle<Object> code_object_;  // This handle will be patched with the code
-                                // object on installation.
+  // This handle will be patched with the code object on installation.
+  Handle<Object> code_object_;
 
   // Helper functions for generating invokes.
   void InvokePrologue(const ParameterCount& expected,