diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 504c141..37c060c 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -357,6 +357,10 @@
     StartAttributeStream("kind") << barrier->GetBarrierKind();
   }
 
+  void VisitMonitorOperation(HMonitorOperation* monitor) OVERRIDE {
+    StartAttributeStream("kind") << (monitor->IsEnter() ? "enter" : "exit");
+  }
+
   void VisitLoadClass(HLoadClass* load_class) OVERRIDE {
     StartAttributeStream("gen_clinit_check") << std::boolalpha
         << load_class->MustGenerateClinitCheck() << std::noboolalpha;