diff --git a/libutils/include/utils/Thread.h b/libutils/include/utils/Thread.h
index fc67656b4..5cf6b47a5 100644
--- a/libutils/include/utils/Thread.h
+++ b/libutils/include/utils/Thread.h
@@ -42,7 +42,9 @@ class Thread : virtual public RefBase
 {
 public:
     // Create a Thread object, but doesn't create or start the associated
-    // thread. See the run() method.
+    // thread. See the run() method. This object must be used with RefBase/sp,
+    // like any other RefBase object, because they are conventionally promoted
+    // from bare pointers (Thread::run is particularly problematic here).
     explicit            Thread(bool canCallJava = true);
     virtual             ~Thread();