diff --git a/compiler/optimizing/codegen_test_utils.h b/compiler/optimizing/codegen_test_utils.h
index 31cd204..00a16fe 100644
--- a/compiler/optimizing/codegen_test_utils.h
+++ b/compiler/optimizing/codegen_test_utils.h
@@ -243,7 +243,7 @@
   GraphChecker graph_checker(graph);
   graph_checker.Run();
   if (!graph_checker.IsValid()) {
-    for (const auto& error : graph_checker.GetErrors()) {
+    for (const std::string& error : graph_checker.GetErrors()) {
       std::cout << error << std::endl;
     }
   }