diff --git a/repos/os/src/lib/vfs/tap/nic_file_system.h b/repos/os/src/lib/vfs/tap/nic_file_system.h
index 43af74ac3c..7e657f375c 100644
--- a/repos/os/src/lib/vfs/tap/nic_file_system.h
+++ b/repos/os/src/lib/vfs/tap/nic_file_system.h
@@ -53,8 +53,8 @@ class Vfs::Nic_file_system::Nic_vfs_handle : public Single_vfs_handle
 		using Read_result  = File_io_service::Read_result;
 		using Write_result = File_io_service::Write_result;
 
-		enum { PKT_SIZE = Nic::Packet_allocator::DEFAULT_PACKET_SIZE };
-		enum { BUF_SIZE = Uplink::Session::QUEUE_SIZE * PKT_SIZE };
+		static constexpr size_t PKT_SIZE = Nic::Packet_allocator::DEFAULT_PACKET_SIZE;
+		static constexpr size_t BUF_SIZE = Uplink::Session::QUEUE_SIZE * PKT_SIZE;
 
 		Genode::Env          &_env;
 		Vfs::Env::User       &_vfs_user;
diff --git a/repos/os/src/lib/vfs/tap/uplink_client_base.h b/repos/os/src/lib/vfs/tap/uplink_client_base.h
index 4b2d3224b7..e6974a68ef 100644
--- a/repos/os/src/lib/vfs/tap/uplink_client_base.h
+++ b/repos/os/src/lib/vfs/tap/uplink_client_base.h
@@ -37,8 +37,8 @@ class Genode::Uplink_client_base : Noncopyable
 
 		enum class Write_result { WRITE_SUCCEEDED, WRITE_FAILED };
 
-		enum { PKT_SIZE = Nic::Packet_allocator::DEFAULT_PACKET_SIZE };
-		enum { BUF_SIZE = Uplink::Session::QUEUE_SIZE * PKT_SIZE };
+		static constexpr size_t PKT_SIZE = Nic::Packet_allocator::DEFAULT_PACKET_SIZE;
+		static constexpr size_t BUF_SIZE = Uplink::Session::QUEUE_SIZE * PKT_SIZE;
 
 		Env                                  &_env;
 		Vfs::Env::User                       &_vfs_user;