diff --git a/common/test_utils.h b/common/test_utils.h
index 363801f..ba9f5f2 100644
--- a/common/test_utils.h
+++ b/common/test_utils.h
@@ -165,7 +165,7 @@
     unlinker_.reset(new ScopedPathUnlinker(path_));
   }
 
-  const std::string& path() { return path_; }
+  const std::string& path() const { return path_; }
 
  private:
   std::string path_;