diff --git a/redox-rt/src/lib.rs b/redox-rt/src/lib.rs
index 985ca1db8d..43cfb811cf 100644
--- a/redox-rt/src/lib.rs
+++ b/redox-rt/src/lib.rs
@@ -206,25 +206,29 @@ pub unsafe fn initialize(#[cfg(feature = "proc")] proc_fd: FdGuard) {
     {
         *DYNAMIC_PROC_INFO.lock() = DynamicProcInfo {
             pgid: metadata.pgid,
-            egid: metadata.egid,
-            euid: metadata.euid,
             ruid: metadata.ruid,
+            euid: metadata.euid,
+            suid: metadata.suid,
+            egid: metadata.egid,
             rgid: metadata.rgid,
+            sgid: metadata.sgid,
         };
     }
 }
 
 pub(crate) struct StaticProcInfo {
     pid: u32,
-    ppid: u32,
+    ppid: u32, // TODO: dynamic
     proc_fd: Option<FdGuard>,
 }
 struct DynamicProcInfo {
     pgid: u32,
     euid: u32,
+    suid: u32,
     ruid: u32,
     egid: u32,
     rgid: u32,
+    sgid: u32,
 }
 
 static STATIC_PROC_INFO: SyncUnsafeCell<StaticProcInfo> = SyncUnsafeCell::new(StaticProcInfo {
@@ -234,10 +238,12 @@ static STATIC_PROC_INFO: SyncUnsafeCell<StaticProcInfo> = SyncUnsafeCell::new(St
 });
 static DYNAMIC_PROC_INFO: Mutex<DynamicProcInfo> = Mutex::new(DynamicProcInfo {
     pgid: u32::MAX,
-    euid: u32::MAX,
-    egid: u32::MAX,
     ruid: u32::MAX,
+    euid: u32::MAX,
+    suid: u32::MAX,
     rgid: u32::MAX,
+    egid: u32::MAX,
+    sgid: u32::MAX,
 });
 
 #[inline]
diff --git a/redox-rt/src/proc.rs b/redox-rt/src/proc.rs
index 84a50d6fae..78aa939dde 100644
--- a/redox-rt/src/proc.rs
+++ b/redox-rt/src/proc.rs
@@ -937,10 +937,12 @@ pub unsafe fn make_init() -> &'static FdGuard {
     });
     *DYNAMIC_PROC_INFO.lock() = crate::DynamicProcInfo {
         pgid: 1,
-        egid: 0,
-        euid: 0,
-        rgid: 0,
         ruid: 0,
+        euid: 0,
+        suid: 0,
+        rgid: 0,
+        egid: 0,
+        sgid: 0,
     };
     (*STATIC_PROC_INFO.get()).proc_fd.as_ref().unwrap()
 }
diff --git a/redox-rt/src/protocol.rs b/redox-rt/src/protocol.rs
index 25b9323bd8..6161efe411 100644
--- a/redox-rt/src/protocol.rs
+++ b/redox-rt/src/protocol.rs
@@ -1,14 +1,17 @@
 use bitflags::bitflags;
 
 #[derive(Clone, Copy, Debug, Default)]
+#[repr(C)]
 pub struct ProcMeta {
     pub pid: u32,
     pub pgid: u32,
     pub ppid: u32,
-    pub euid: u32,
     pub ruid: u32,
-    pub egid: u32,
+    pub euid: u32,
+    pub suid: u32,
     pub rgid: u32,
+    pub egid: u32,
+    pub sgid: u32,
     pub ens: u32,
     pub rns: u32,
 }
diff --git a/redox-rt/src/sys.rs b/redox-rt/src/sys.rs
index 9d8565468e..8f299c0379 100644
--- a/redox-rt/src/sys.rs
+++ b/redox-rt/src/sys.rs
@@ -14,7 +14,7 @@ use crate::{
     proc::FdGuard,
     protocol::{ProcCall, ProcKillTarget, WaitFlags},
     signal::tmp_disable_signals,
-    Tcb, DYNAMIC_PROC_INFO,
+    DynamicProcInfo, Tcb, DYNAMIC_PROC_INFO,
 };
 
 #[inline]
@@ -189,14 +189,18 @@ pub fn get_umask() -> u32 {
     UMASK.load(Ordering::Acquire)
 }
 
-pub fn posix_setresugid(
-    ruid: Option<u32>,
-    euid: Option<u32>,
-    suid: Option<u32>,
-    rgid: Option<u32>,
-    egid: Option<u32>,
-    sgid: Option<u32>,
-) -> Result<()> {
+/// Real/Effective/Set-User/Group ID
+pub struct Resugid<T> {
+    pub ruid: T,
+    pub euid: T,
+    pub suid: T,
+    pub rgid: T,
+    pub egid: T,
+    pub sgid: T,
+}
+
+/// Sets [res][ug]id, fields that are None will be unchanged.
+pub fn posix_setresugid(ids: &Resugid<Option<u32>>) -> Result<()> {
     // TODO: not sure how "tmp" an IPC call is?
     let _sig_guard = tmp_disable_signals();
     let mut guard = DYNAMIC_PROC_INFO.lock();
@@ -205,12 +209,12 @@ pub fn posix_setresugid(
     plain::slice_from_mut_bytes(&mut buf)
         .unwrap()
         .copy_from_slice(&[
-            ruid.unwrap_or(u32::MAX),
-            euid.unwrap_or(u32::MAX),
-            suid.unwrap_or(u32::MAX),
-            rgid.unwrap_or(u32::MAX),
-            egid.unwrap_or(u32::MAX),
-            sgid.unwrap_or(u32::MAX),
+            ids.ruid.unwrap_or(u32::MAX),
+            ids.euid.unwrap_or(u32::MAX),
+            ids.suid.unwrap_or(u32::MAX),
+            ids.rgid.unwrap_or(u32::MAX),
+            ids.egid.unwrap_or(u32::MAX),
+            ids.sgid.unwrap_or(u32::MAX),
         ]);
 
     proc_call(
@@ -219,38 +223,46 @@ pub fn posix_setresugid(
         &[ProcCall::SetResugid as usize],
     )?;
 
-    if let Some(ruid) = ruid {
+    if let Some(ruid) = ids.ruid {
         guard.ruid = ruid;
     }
-    if let Some(euid) = euid {
+    if let Some(euid) = ids.euid {
         guard.euid = euid;
     }
-    // TODO: suid?
-    if let Some(rgid) = rgid {
+    if let Some(suid) = ids.suid {
+        guard.suid = suid;
+    }
+    if let Some(rgid) = ids.rgid {
         guard.rgid = rgid;
     }
-    if let Some(egid) = egid {
+    if let Some(egid) = ids.egid {
         guard.egid = egid;
     }
-    // TODO: sgid?
+    if let Some(sgid) = ids.sgid {
+        guard.sgid = sgid;
+    }
 
     Ok(())
 }
-pub fn posix_getruid() -> u32 {
-    let _guard = tmp_disable_signals();
-    DYNAMIC_PROC_INFO.lock().ruid
-}
-pub fn posix_getrgid() -> u32 {
-    let _guard = tmp_disable_signals();
-    DYNAMIC_PROC_INFO.lock().rgid
-}
-pub fn posix_geteuid() -> u32 {
-    let _guard = tmp_disable_signals();
-    DYNAMIC_PROC_INFO.lock().euid
-}
-pub fn posix_getegid() -> u32 {
-    let _guard = tmp_disable_signals();
-    DYNAMIC_PROC_INFO.lock().egid
+pub fn posix_getresugid() -> Resugid<u32> {
+    let _sig_guard = tmp_disable_signals();
+    let DynamicProcInfo {
+        ruid,
+        euid,
+        suid,
+        rgid,
+        egid,
+        sgid,
+        ..
+    } = *DYNAMIC_PROC_INFO.lock();
+    Resugid {
+        ruid,
+        euid,
+        suid,
+        rgid,
+        egid,
+        sgid,
+    }
 }
 pub fn posix_exit(status: i32) -> ! {
     proc_call(
diff --git a/src/platform/redox/exec.rs b/src/platform/redox/exec.rs
index 660a67332e..c7f9aed4b9 100644
--- a/src/platform/redox/exec.rs
+++ b/src/platform/redox/exec.rs
@@ -16,6 +16,7 @@ use crate::{
 
 use redox_rt::{
     proc::{ExtraInfo, FdGuard, FexecResult, InterpOverride},
+    sys::Resugid,
     RtTcb,
 };
 use syscall::{data::Stat, error::*, flag::*};
@@ -120,12 +121,11 @@ pub fn execve(
 
     let mut stat = Stat::default();
     syscall::fstat(*image_file as usize, &mut stat)?;
-    let uid = redox_rt::sys::posix_getruid() as usize;
-    let gid = redox_rt::sys::posix_getrgid() as usize;
+    let Resugid { ruid, rgid, .. } = redox_rt::sys::posix_getresugid();
 
-    let mode = if uid == stat.st_uid as usize {
+    let mode = if ruid == stat.st_uid {
         (stat.st_mode >> 3 * 2) & 0o7
-    } else if gid == stat.st_gid as usize {
+    } else if rgid == stat.st_gid {
         (stat.st_mode >> 3 * 1) & 0o7
     } else {
         stat.st_mode & 0o7
diff --git a/src/platform/redox/libredox.rs b/src/platform/redox/libredox.rs
index 29efa7caf8..5e5bcad345 100644
--- a/src/platform/redox/libredox.rs
+++ b/src/platform/redox/libredox.rs
@@ -227,19 +227,19 @@ pub unsafe extern "C" fn redox_get_pid_v1() -> RawResult {
 
 #[no_mangle]
 pub unsafe extern "C" fn redox_get_euid_v1() -> RawResult {
-    redox_rt::sys::posix_geteuid() as _
+    redox_rt::sys::posix_getresugid().euid as _
 }
 #[no_mangle]
 pub unsafe extern "C" fn redox_get_ruid_v1() -> RawResult {
-    redox_rt::sys::posix_getruid() as _
+    redox_rt::sys::posix_getresugid().ruid as _
 }
 #[no_mangle]
 pub unsafe extern "C" fn redox_get_egid_v1() -> RawResult {
-    redox_rt::sys::posix_getegid() as _
+    redox_rt::sys::posix_getresugid().egid as _
 }
 #[no_mangle]
 pub unsafe extern "C" fn redox_get_rgid_v1() -> RawResult {
-    redox_rt::sys::posix_getrgid() as _
+    redox_rt::sys::posix_getresugid().rgid as _
 }
 #[no_mangle]
 pub unsafe extern "C" fn redox_setrens_v1(rns: usize, ens: usize) -> RawResult {
diff --git a/src/platform/redox/mod.rs b/src/platform/redox/mod.rs
index c2fee23574..07612a5d42 100644
--- a/src/platform/redox/mod.rs
+++ b/src/platform/redox/mod.rs
@@ -5,7 +5,7 @@ use core::{
 };
 use redox_rt::{
     protocol::{wifstopped, wstopsig, WaitFlags},
-    sys::WaitpidTarget,
+    sys::{Resugid, WaitpidTarget},
     RtTcb,
 };
 use syscall::{
@@ -104,12 +104,11 @@ impl Pal for Sys {
 
         syscall::fstat(*fd as usize, &mut stat)?;
 
-        let uid = redox_rt::sys::posix_getruid() as usize;
-        let gid = redox_rt::sys::posix_getrgid() as usize;
+        let Resugid { ruid, rgid, .. } = redox_rt::sys::posix_getresugid();
 
-        let perms = if stat.st_uid as usize == uid {
+        let perms = if stat.st_uid == ruid {
             stat.st_mode >> (3 * 2 & 0o7)
-        } else if stat.st_gid as usize == gid {
+        } else if stat.st_gid == rgid {
             stat.st_mode >> (3 * 1 & 0o7)
         } else {
             stat.st_mode & 0o7
@@ -412,15 +411,15 @@ impl Pal for Sys {
     }
 
     fn getegid() -> gid_t {
-        redox_rt::sys::posix_getegid() as gid_t
+        redox_rt::sys::posix_getresugid().egid as gid_t
     }
 
     fn geteuid() -> uid_t {
-        redox_rt::sys::posix_geteuid() as uid_t
+        redox_rt::sys::posix_getresugid().euid as uid_t
     }
 
     fn getgid() -> gid_t {
-        redox_rt::sys::posix_getrgid() as gid_t
+        redox_rt::sys::posix_getresugid().rgid as gid_t
     }
 
     unsafe fn getgroups(size: c_int, list: *mut gid_t) -> Result<c_int> {
@@ -528,7 +527,7 @@ impl Pal for Sys {
     }
 
     fn getuid() -> uid_t {
-        redox_rt::sys::posix_getruid() as uid_t
+        redox_rt::sys::posix_getresugid().ruid as uid_t
     }
 
     fn lchown(path: CStr, owner: uid_t, group: gid_t) -> Result<()> {
@@ -858,26 +857,26 @@ impl Pal for Sys {
     }
 
     fn setresgid(rgid: gid_t, egid: gid_t, sgid: gid_t) -> Result<()> {
-        redox_rt::sys::posix_setresugid(
-            None,
-            None,
-            None,
-            cvt_uid(rgid)?,
-            cvt_uid(egid)?,
-            cvt_uid(sgid)?,
-        )?;
+        redox_rt::sys::posix_setresugid(&Resugid {
+            ruid: None,
+            euid: None,
+            suid: None,
+            rgid: cvt_uid(rgid)?,
+            egid: cvt_uid(egid)?,
+            sgid: cvt_uid(sgid)?,
+        })?;
         Ok(())
     }
 
     fn setresuid(ruid: uid_t, euid: uid_t, suid: uid_t) -> Result<()> {
-        redox_rt::sys::posix_setresugid(
-            cvt_uid(ruid)?,
-            cvt_uid(euid)?,
-            cvt_uid(suid)?,
-            None,
-            None,
-            None,
-        )?;
+        redox_rt::sys::posix_setresugid(&Resugid {
+            ruid: cvt_uid(ruid)?,
+            euid: cvt_uid(euid)?,
+            suid: cvt_uid(suid)?,
+            rgid: None,
+            egid: None,
+            sgid: None,
+        })?;
         Ok(())
     }