diff --git a/cache/clock_cache.cc b/cache/clock_cache.cc
index 3fa4c3659..89173834e 100644
--- a/cache/clock_cache.cc
+++ b/cache/clock_cache.cc
@@ -234,7 +234,7 @@ struct CleanupContext {
 };
 
 // A cache shard which maintains its own CLOCK cache.
-class ClockCacheShard : public CacheShard {
+class ClockCacheShard final : public CacheShard {
  public:
   // Hash map type.
   typedef tbb::concurrent_hash_map<CacheKey, CacheHandle*, CacheKey> HashTable;
@@ -672,7 +672,7 @@ void ClockCacheShard::EraseUnRefEntries() {
   Cleanup(context);
 }
 
-class ClockCache : public ShardedCache {
+class ClockCache final : public ShardedCache {
  public:
   ClockCache(size_t capacity, int num_shard_bits, bool strict_capacity_limit)
       : ShardedCache(capacity, num_shard_bits, strict_capacity_limit) {
diff --git a/cache/lru_cache.h b/cache/lru_cache.h
index 665a97a5c..0d9a31748 100644
--- a/cache/lru_cache.h
+++ b/cache/lru_cache.h
@@ -165,7 +165,7 @@ class LRUHandleTable {
 };
 
 // A single shard of sharded cache.
-class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard : public CacheShard {
+class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
  public:
   LRUCacheShard(size_t capacity, bool strict_capacity_limit,
                 double high_pri_pool_ratio, bool use_adaptive_mutex);
@@ -284,7 +284,11 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard : public CacheShard {
   mutable port::Mutex mutex_;
 };
 
-class LRUCache : public ShardedCache {
+class LRUCache
+#ifdef NDEBUG
+    final
+#endif
+    : public ShardedCache {
  public:
   LRUCache(size_t capacity, int num_shard_bits, bool strict_capacity_limit,
            double high_pri_pool_ratio,