diff --git a/compiler/driver/compiler_driver.h b/compiler/driver/compiler_driver.h
index 12463a9..817da17 100644
--- a/compiler/driver/compiler_driver.h
+++ b/compiler/driver/compiler_driver.h
@@ -564,8 +564,11 @@
   class ProfileData {
    public:
     ProfileData() : count_(0), method_size_(0), percent_(0) {}
-    ProfileData(std::string method_name, uint32_t count, uint32_t method_size, double percent) :
+    ProfileData(const std::string& method_name, uint32_t count, uint32_t method_size, double percent) :
       method_name_(method_name), count_(count), method_size_(method_size), percent_(percent) {
+      // TODO: currently method_size_ and count_ are unused.
+      UNUSED(method_size_);
+      UNUSED(count_);
     }
 
     bool IsAbove(double v) const { return percent_ >= v; }