diff --git a/lib/active_storage/service/db_service.rb b/lib/active_storage/service/db_service.rb
index 92677dd..c86ade6 100644
--- a/lib/active_storage/service/db_service.rb
+++ b/lib/active_storage/service/db_service.rb
@@ -19,7 +19,7 @@ class Service::DBService < Service
     # :nocov:
 
     def initialize(public: false, **)
-      @chunk_size = ENV.fetch("ASDB_CHUNK_SIZE") { 1.megabytes }
+      @chunk_size = ENV.fetch("ASDB_CHUNK_SIZE") { 1.megabytes }.to_i
       @public = public
     end