diff --git a/services/surfaceflinger/FrameTracker.h b/services/surfaceflinger/FrameTracker.h
index b4a9fd6..555dcc1 100644
--- a/services/surfaceflinger/FrameTracker.h
+++ b/services/surfaceflinger/FrameTracker.h
@@ -90,7 +90,7 @@
     void logAndResetStats(const String8& name);
 
     // dumpStats dump appends the current frame display time history to the result string.
-    void dumpStats(String8& result) const;
+    void dumpStats(std::string& result) const;
 
 private:
     struct FrameRecord {