diff --git a/Cargo.lock b/Cargo.lock
index 1b0923d..940f247 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -160,7 +160,7 @@ dependencies = [
  "http 1.0.0",
  "http-body 1.0.0",
  "http-body-util",
- "hyper 1.1.0",
+ "hyper 1.2.0",
  "hyper-util",
  "itoa",
  "matchit",
@@ -260,12 +260,9 @@ checksum = "a2bd12c1caf447e69cd4528f47f94d203fd2582878ecb9e9465484c4148a8223"
 
 [[package]]
 name = "cc"
-version = "1.0.83"
+version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
-dependencies = [
- "libc",
-]
+checksum = "7f9fa1897e4325be0d68d48df6aa1a71ac2ed4d27723887e7754192705350730"
 
 [[package]]
 name = "cfg-if"
@@ -608,9 +605,9 @@ dependencies = [
 
 [[package]]
 name = "hyper"
-version = "1.1.0"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fb5aa53871fc917b1a9ed87b683a5d86db645e23acb32c2e0785a353e522fb75"
+checksum = "186548d73ac615b32a73aafe38fb4f56c0d340e110e5a200bcadbaf2e199263a"
 dependencies = [
  "bytes",
  "futures-channel",
@@ -622,6 +619,7 @@ dependencies = [
  "httpdate",
  "itoa",
  "pin-project-lite",
+ "smallvec",
  "tokio",
 ]
 
@@ -647,7 +645,7 @@ dependencies = [
  "futures-util",
  "http 1.0.0",
  "http-body 1.0.0",
- "hyper 1.1.0",
+ "hyper 1.2.0",
  "pin-project-lite",
  "socket2",
  "tokio",
@@ -1130,6 +1128,12 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "smallvec"
+version = "1.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6ecd384b10a64542d77071bd64bd7b231f4ed5940fba55e98c3de13824cf3d7"
+
 [[package]]
 name = "socket2"
 version = "0.5.5"
diff --git a/crates/rsjudge-runner/examples/demo.rs b/crates/rsjudge-runner/examples/demo.rs
index 63015dd..76e9b05 100644
--- a/crates/rsjudge-runner/examples/demo.rs
+++ b/crates/rsjudge-runner/examples/demo.rs
@@ -1,10 +1,17 @@
 use std::process::Command;
 
+use anyhow::anyhow;
 use rsjudge_runner::{
     user::{builder, runner},
     RunAs,
 };
+use uzers::{get_current_uid, get_user_by_uid};
 fn main() -> anyhow::Result<()> {
+    let self_output = Command::new("id")
+        .run_as(&get_user_by_uid(get_current_uid()).ok_or(anyhow!("invalid user"))?)
+        .output()?;
+    println!("{}", String::from_utf8_lossy(&self_output.stdout));
+
     let builder_output = Command::new("id").run_as(builder()?).output()?;
     println!("{}", String::from_utf8_lossy(&builder_output.stdout));
 
diff --git a/crates/rsjudge-runner/src/lib.rs b/crates/rsjudge-runner/src/lib.rs
index 35981c6..ac12c86 100644
--- a/crates/rsjudge-runner/src/lib.rs
+++ b/crates/rsjudge-runner/src/lib.rs
@@ -12,11 +12,17 @@ impl RunAs for Command {
     fn run_as(&mut self, user: &User) -> &mut Command {
         let uid = user.uid();
         let gid = user.primary_group_id();
+        let groups: Vec<_> = user
+            .groups()
+            .unwrap_or_default()
+            .into_iter()
+            .map(|g| g.gid().into())
+            .collect();
 
         self.uid(uid).gid(gid);
         unsafe {
             self.pre_exec(move || {
-                setgroups(&[gid.into()])?;
+                setgroups(&groups)?;
                 Ok(())
             })
         };
diff --git a/crates/rsjudge-runner/src/user.rs b/crates/rsjudge-runner/src/user.rs
index 3e7eb96..b512ff8 100644
--- a/crates/rsjudge-runner/src/user.rs
+++ b/crates/rsjudge-runner/src/user.rs
@@ -27,28 +27,3 @@ pub fn runner() -> anyhow::Result<&'static User> {
         .as_ref()
         .ok_or_else(|| anyhow!("No such user: rsjudge-runner"))
 }
-
-#[cfg(all(test, unix))]
-mod tests {
-    use std::{os::unix::process::CommandExt, process::Command};
-
-    use super::*;
-
-    #[test]
-    #[ignore = "Requires additional users."]
-    fn test_uid() -> anyhow::Result<()> {
-        let builder = builder()?;
-        let builder_output = Command::new("id")
-            .uid(builder.uid())
-            .gid(builder.primary_group_id())
-            .output()?;
-        println!("{}", String::from_utf8_lossy(&builder_output.stdout));
-        let runner = runner()?;
-        let runner_output = Command::new("id")
-            .uid(runner.uid())
-            .gid(runner.primary_group_id())
-            .output()?;
-        println!("{}", String::from_utf8_lossy(&runner_output.stdout));
-        Ok(())
-    }
-}