diff --git a/compiler/utils/assembler.cc b/compiler/utils/assembler.cc
index 36342c6..b016e74 100644
--- a/compiler/utils/assembler.cc
+++ b/compiler/utils/assembler.cc
@@ -41,8 +41,8 @@
   contents_ = NewContents(kInitialBufferCapacity);
   cursor_ = contents_;
   limit_ = ComputeLimit(contents_, kInitialBufferCapacity);
-  fixup_ = NULL;
-  slow_path_ = NULL;
+  fixup_ = nullptr;
+  slow_path_ = nullptr;
 #ifndef NDEBUG
   has_ensured_capacity_ = false;
   fixups_processed_ = false;
@@ -61,7 +61,7 @@
 
 void AssemblerBuffer::ProcessFixups(const MemoryRegion& region) {
   AssemblerFixup* fixup = fixup_;
-  while (fixup != NULL) {
+  while (fixup != nullptr) {
     fixup->Process(region, fixup->position());
     fixup = fixup->previous();
   }
@@ -127,7 +127,7 @@
       return new x86_64::X86_64Assembler();
     default:
       LOG(FATAL) << "Unknown InstructionSet: " << instruction_set;
-      return NULL;
+      return nullptr;
   }
 }