diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index b47549a..f562113 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -236,7 +236,7 @@
     return false;
   }
 
-  int NumberOfBackEdges() const {
+  size_t NumberOfBackEdges() const {
     return back_edges_.Size();
   }