diff --git a/libartbase/base/file_utils.h b/libartbase/base/file_utils.h
index c5e55d1..1594aee 100644
--- a/libartbase/base/file_utils.h
+++ b/libartbase/base/file_utils.h
@@ -32,12 +32,12 @@
 // Find $ANDROID_ROOT, /system, or abort.
 std::string GetAndroidRoot();
 // Find $ANDROID_ROOT, /system, or return an empty string.
-std::string GetAndroidRootSafe(std::string* error_msg);
+std::string GetAndroidRootSafe(/*out*/ std::string* error_msg);
 
 // Find $ANDROID_DATA, /data, or abort.
 const char* GetAndroidData();
 // Find $ANDROID_DATA, /data, or return null.
-const char* GetAndroidDataSafe(std::string* error_msg);
+const char* GetAndroidDataSafe(/*out*/ std::string* error_msg);
 
 // Returns the default boot image location (ANDROID_ROOT/framework/boot.art).
 // Returns an empty string if ANDROID_ROOT is not set.