diff --git a/compiler/utils/assembler.h b/compiler/utils/assembler.h
index ebafd3d..2e3a47b 100644
--- a/compiler/utils/assembler.h
+++ b/compiler/utils/assembler.h
@@ -156,7 +156,7 @@
 // Parent of all queued slow paths, emitted during finalization
 class SlowPath {
  public:
-  SlowPath() : next_(NULL) {}
+  SlowPath() : next_(nullptr) {}
   virtual ~SlowPath() {}
 
   Label* Continuation() { return &continuation_; }
@@ -216,20 +216,20 @@
   }
 
   void EnqueueSlowPath(SlowPath* slowpath) {
-    if (slow_path_ == NULL) {
+    if (slow_path_ == nullptr) {
       slow_path_ = slowpath;
     } else {
       SlowPath* cur = slow_path_;
-      for ( ; cur->next_ != NULL ; cur = cur->next_) {}
+      for ( ; cur->next_ != nullptr ; cur = cur->next_) {}
       cur->next_ = slowpath;
     }
   }
 
   void EmitSlowPaths(Assembler* sp_asm) {
     SlowPath* cur = slow_path_;
-    SlowPath* next = NULL;
-    slow_path_ = NULL;
-    for ( ; cur != NULL ; cur = next) {
+    SlowPath* next = nullptr;
+    slow_path_ = nullptr;
+    for ( ; cur != nullptr ; cur = next) {
       cur->Emit(sp_asm);
       next = cur->next_;
       delete cur;
@@ -489,14 +489,14 @@
   virtual void GetCurrentThread(FrameOffset dest_offset,
                                 ManagedRegister scratch) = 0;
 
-  // Set up out_reg to hold a Object** into the handle scope, or to be NULL if the
+  // Set up out_reg to hold a Object** into the handle scope, or to be null if the
   // value is null and null_allowed. in_reg holds a possibly stale reference
   // that can be used to avoid loading the handle scope entry to see if the value is
-  // NULL.
+  // null.
   virtual void CreateHandleScopeEntry(ManagedRegister out_reg, FrameOffset handlescope_offset,
                                ManagedRegister in_reg, bool null_allowed) = 0;
 
-  // Set up out_off to hold a Object** into the handle scope, or to be NULL if the
+  // Set up out_off to hold a Object** into the handle scope, or to be null if the
   // value is null and null_allowed.
   virtual void CreateHandleScopeEntry(FrameOffset out_off, FrameOffset handlescope_offset,
                                ManagedRegister scratch, bool null_allowed) = 0;