diff --git a/utilities/persistent_cache/block_cache_tier.h b/utilities/persistent_cache/block_cache_tier.h
index d0767abd6..cc917c0f4 100644
--- a/utilities/persistent_cache/block_cache_tier.h
+++ b/utilities/persistent_cache/block_cache_tier.h
@@ -68,11 +68,8 @@ class BlockCacheTier : public PersistentCacheTier {
 
   void TEST_Flush() override {
     while (insert_ops_.Size()) {
-#ifdef OS_WIN
-      Sleep(1000);
-#else
-      /* sleep override */ sleep(1);
-#endif
+      /* sleep override */
+      Env::Default()->SleepForMicroseconds(1000000);
     }
   }
 
diff --git a/utilities/persistent_cache/persistent_cache_tier.h b/utilities/persistent_cache/persistent_cache_tier.h
index de088feb0..2717742a2 100644
--- a/utilities/persistent_cache/persistent_cache_tier.h
+++ b/utilities/persistent_cache/persistent_cache_tier.h
@@ -200,7 +200,8 @@ struct PersistentCacheConfig {
   // file size in order to avoid dead lock.
   size_t write_buffer_count() const {
     assert(write_buffer_size);
-    return (writer_qdepth + writer_qdepth/5) * cache_file_size / write_buffer_size;
+    return static_cast<size_t>((writer_qdepth + 1.2) * cache_file_size /
+                               write_buffer_size);
   }
 
   // writer-dispatch-size