diff --git a/Cargo.lock b/Cargo.lock
index d57381b..bfe938f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -31,9 +31,9 @@ dependencies = [
 
 [[package]]
 name = "autocfg"
-version = "1.3.0"
+version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0c4b4d0bd25bd0b74681c0ad21497610ce1b7c91b1022cd21c80c6fbdd9476b0"
+checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
 
 [[package]]
 name = "bga"
@@ -191,9 +191,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.158"
+version = "0.2.159"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d8adc4bb1803a324070e64a98ae98f38934d91957a99cfb3a43dcbc01bc56439"
+checksum = "561d97a539a36e26a9a5fad1ea11a3039a67714694aaa379433e580854bc3dc5"
 
 [[package]]
 name = "lock_api"
@@ -207,9 +207,12 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.19.0"
+version = "1.20.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
+checksum = "82881c4be219ab5faaf2ad5e5e5ecdff8c66bd7402ca3160975c93b24961afd1"
+dependencies = [
+ "portable-atomic",
+]
 
 [[package]]
 name = "parking_lot"
@@ -242,6 +245,12 @@ dependencies = [
  "postcard",
 ]
 
+[[package]]
+name = "portable-atomic"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc9c68a3f6da06753e9335d63e27f6b9754dd1920d941135b7ea8224f141adb2"
+
 [[package]]
 name = "postcard"
 version = "1.0.10"
@@ -287,9 +296,9 @@ dependencies = [
 
 [[package]]
 name = "redox_syscall"
-version = "0.5.3"
+version = "0.5.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a908a6e00f1fdd0dfd9c0eb08ce85126f6d8bbda50017e74bc4a4b7d4a926a4"
+checksum = "9b6dfecf2c74bce2466cabf93f6664d6998a69eb21e39f4207930065b27b771f"
 dependencies = [
  "bitflags",
 ]
@@ -330,8 +339,6 @@ checksum = "61697e0a1c7e512e84a621326239844a24d8207b4669b41bc18b32ea5cbf988b"
 [[package]]
 name = "serde"
 version = "1.0.210"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c8e3592472072e6e22e0a54d5904d9febf8508f65fb8552499a1abc7d1078c3a"
 dependencies = [
  "serde_derive",
 ]
@@ -339,12 +346,10 @@ dependencies = [
 [[package]]
 name = "serde_derive"
 version = "1.0.210"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "243902eda00fad750862fc144cea25caca5e20d615af0a81bee94ca738f1df1f"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.77",
+ "syn 2.0.79",
 ]
 
 [[package]]
@@ -381,9 +386,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.77"
+version = "2.0.79"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9f35bcdf61fd8e7be6caf75f429fdca8beb3ed76584befb503b1569faee373ed"
+checksum = "89132cd0bf050864e1d38dc3bbc07a0eb8e7530af26344d3d2bbbef83499f590"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -414,9 +419,9 @@ checksum = "2c591d83f69777866b9126b24c6dd9a18351f177e49d625920d19f989fd31cf8"
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.12"
+version = "1.0.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"
 
 [[package]]
 name = "version_check"
@@ -529,5 +534,5 @@ checksum = "fa4f8080344d4671fb4e831a13ad1e68092748387dfc4f55e356242fae12ce3e"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.77",
+ "syn 2.0.79",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 156a15c..975ccd7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,3 +15,7 @@ rhexdump = "0.2.0"
 syslog_rpc = { version = "0.1.0", path = "../syslog/syslog_rpc" }
 volatile = { version = "0.6.1", features = ["unstable"] }
 x86_64 = "0.15.1"
+
+[patch.crates-io]
+serde = { path = "../serde/serde" }
+serde_derive = { path = "../serde/serde_derive" }
diff --git a/src/main.rs b/src/main.rs
index 50a6fca..35990b2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,7 +24,7 @@ use std::{
     borrow::Cow,
     collections::{HashMap, VecDeque},
     fmt::{self, Write},
-    os::mikros::{address_space::ACTIVE_SPACE, ipc, syscalls},
+    os::mikros::{address_space::ACTIVE_SPACE, ipc, syscalls, Errno},
 };
 
 use fontdue::{
@@ -336,7 +336,7 @@ impl fmt::Write for FramebufferWriter {
 struct DevServ;
 
 impl dev_driver_rpc::Server for DevServ {
-    fn open(&self, _path: &std::path::Path) -> Result<u64, ()> {
+    fn open(&self, _path: &std::path::Path) -> Result<u64, Errno> {
         Ok(0)
     }
 }
@@ -351,13 +351,13 @@ impl file_rpc::Server for FileServ {
         &self,
         _fd: u64,
         _len: usize,
-    ) -> std::result::Result<std::borrow::Cow<'_, [u8]>, ()> {
-        Err(())
+    ) -> std::result::Result<std::borrow::Cow<'_, [u8]>, Errno> {
+        Err(Errno::ENOSYS)
     }
 
     #[allow(clippy::significant_drop_tightening)]
-    fn write(&self, _fd: u64, data: &[u8]) -> Result<(), ()> {
-        let string = str::from_utf8(data).map_err(|_| ())?;
+    fn write(&self, _fd: u64, data: &[u8]) -> Result<(), Errno> {
+        let string = str::from_utf8(data).map_err(|_| Errno::EINVALDAT)?;
         let mut fbwriter = self.fbwriter.lock();
         let mut fbuffer = self.fbuffer.lock();
         let _ = fbwriter.write_str(string); // never errors
@@ -365,17 +365,17 @@ impl file_rpc::Server for FileServ {
         Ok(())
     }
 
-    fn close(&self, _fd: u64) {}
+    fn close(&self, _fd: u64) -> Result<(), Errno> { Ok(()) }
 
-    fn size(&self, _fd: u64) -> Option<u64> {
-        None
+    fn size(&self, _fd: u64) -> Result<u64, Errno> {
+        Err(Errno::ENOSYS)
     }
 
-    fn dup(&self, fd: u64) -> Option<u64> {
-        Some(fd)
+    fn dup(&self, fd: u64) -> Result<u64, Errno> {
+        Ok(fd)
     }
 
-    fn seek(&self, _fd: u64, _pos: file_rpc::SeekFrom) -> u64 { 0 }
+    fn seek(&self, _fd: u64, _pos: file_rpc::SeekFrom) -> Result<u64, Errno> { Err(Errno::ESPIPE) }
 }
 
 fn main() {