diff --git a/db/db_iter.cc b/db/db_iter.cc
index 33f926ce07f64e8ed0a5d08185d66ec348e7a841..16fcf9f793eacecfdc527ff14f6cfcf850c78ab2 100644
--- a/db/db_iter.cc
+++ b/db/db_iter.cc
@@ -50,7 +50,7 @@ static void DumpInternalIter(Iterator* iter) {
 // combines multiple entries for the same userkey found in the DB
 // representation into a single entry while accounting for sequence
 // numbers, deletion markers, overwrites, etc.
-class DBIter: public Iterator {
+class DBIter final: public Iterator {
  public:
   // The following is grossly complicated. TODO: clean it up
   // Which direction is the iterator currently moving?