diff --git a/util/thread_local.h b/util/thread_local.h
index a037a9ceb..6884ed138 100644
--- a/util/thread_local.h
+++ b/util/thread_local.h
@@ -26,13 +26,14 @@ namespace rocksdb {
 // (2) a ThreadLocalPtr is destroyed
 typedef void (*UnrefHandler)(void* ptr);
 
-// Thread local storage that only stores value of pointer type. The storage
-// distinguish data coming from different thread and different ThreadLocalPtr
-// instances. For example, if a regular thread_local variable A is declared
-// in DBImpl, two DBImpl objects would share the same A. ThreadLocalPtr avoids
-// the confliction. The total storage size equals to # of threads * # of
-// ThreadLocalPtr instances. It is not efficient in terms of space, but it
-// should serve most of our use cases well and keep code simple.
+// ThreadLocalPtr stores only values of pointer type.  Different from
+// the usual thread-local-storage, ThreadLocalPtr has the ability to
+// distinguish data coming from different threads and different
+// ThreadLocalPtr instances.  For example, if a regular thread_local
+// variable A is declared in DBImpl, two DBImpl objects would share
+// the same A.  However, a ThreadLocalPtr that is defined under the
+// scope of DBImpl can avoid such confliction.  As a result, its memory
+// usage would be O(# of threads * # of ThreadLocalPtr instances).
 class ThreadLocalPtr {
  public:
   explicit ThreadLocalPtr(UnrefHandler handler = nullptr);