diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 13e0e162cb..715a4a3214 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -131,7 +131,7 @@ HDeoptimize* HBasicBlock::CreateDeoptimize(
 }
 
 
-HSimulate* HBasicBlock::CreateSimulate(int id) {
+HSimulate* HBasicBlock::CreateSimulate(int ast_id) {
   ASSERT(HasEnvironment());
   HEnvironment* environment = last_environment();
   ASSERT(id == AstNode::kNoNumber ||
@@ -140,7 +140,7 @@ HSimulate* HBasicBlock::CreateSimulate(int id) {
   int push_count = environment->push_count();
   int pop_count = environment->pop_count();
 
-  HSimulate* instr = new(zone()) HSimulate(id, pop_count);
+  HSimulate* instr = new(zone()) HSimulate(ast_id, pop_count);
   for (int i = push_count - 1; i >= 0; --i) {
     instr->AddPushedValue(environment->ExpressionStackAt(i));
   }
@@ -194,7 +194,7 @@ void HBasicBlock::SetInitialEnvironment(HEnvironment* env) {
 }
 
 
-void HBasicBlock::SetJoinId(int id) {
+void HBasicBlock::SetJoinId(int ast_id) {
   int length = predecessors_.length();
   ASSERT(length > 0);
   for (int i = 0; i < length; i++) {
@@ -204,8 +204,8 @@ void HBasicBlock::SetJoinId(int id) {
     // We only need to verify the ID once.
     ASSERT(i != 0 ||
            predecessor->last_environment()->closure()->shared()
-               ->VerifyBailoutId(id));
-    simulate->set_ast_id(id);
+               ->VerifyBailoutId(ast_id));
+    simulate->set_ast_id(ast_id);
   }
 }
 
@@ -2328,9 +2328,9 @@ HInstruction* HGraphBuilder::AddInstruction(HInstruction* instr) {
 }
 
 
-void HGraphBuilder::AddSimulate(int id) {
+void HGraphBuilder::AddSimulate(int ast_id) {
   ASSERT(current_block() != NULL);
-  current_block()->AddSimulate(id);
+  current_block()->AddSimulate(ast_id);
 }
 
 
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 78490db11a..26d01c1b65 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -116,14 +116,14 @@ class HBasicBlock: public ZoneObject {
 
   bool HasParentLoopHeader() const { return parent_loop_header_ != NULL; }
 
-  void SetJoinId(int id);
+  void SetJoinId(int ast_id);
 
   void Finish(HControlInstruction* last);
   void FinishExit(HControlInstruction* instruction);
   void Goto(HBasicBlock* block, bool include_stack_check = false);
 
   int PredecessorIndexOf(HBasicBlock* predecessor) const;
-  void AddSimulate(int id) { AddInstruction(CreateSimulate(id)); }
+  void AddSimulate(int ast_id) { AddInstruction(CreateSimulate(ast_id)); }
   void AssignCommonDominator(HBasicBlock* other);
 
   void FinishExitWithDeoptimization(HDeoptimize::UseEnvironment has_uses) {
@@ -156,7 +156,7 @@ class HBasicBlock: public ZoneObject {
   void RegisterPredecessor(HBasicBlock* pred);
   void AddDominatedBlock(HBasicBlock* block);
 
-  HSimulate* CreateSimulate(int id);
+  HSimulate* CreateSimulate(int ast_id);
   HDeoptimize* CreateDeoptimize(HDeoptimize::UseEnvironment has_uses);
 
   int block_id_;
@@ -694,7 +694,7 @@ class HGraphBuilder: public AstVisitor {
 
   // Adding instructions.
   HInstruction* AddInstruction(HInstruction* instr);
-  void AddSimulate(int id);
+  void AddSimulate(int ast_id);
 
   // Bailout environment manipulation.
   void Push(HValue* value) { environment()->Push(value); }