diff --git a/src/header/signal/constants.rs b/src/header/signal/constants.rs
new file mode 100644
index 0000000000..247925b29d
--- /dev/null
+++ b/src/header/signal/constants.rs
@@ -0,0 +1,216 @@
+// These constants have the same values on Redox and Linux.
+
+// Default actions are:
+// - T (Abnormal termination of the process)
+// - A (Abnormal termination of the process with additional actions)
+// - I (Ignore the signal)
+// - S (Stop the process)
+// - C (Continue the process, if it is stopped; otherwise, ignore the signal)
+
+/// Hangup.
+/// Default action: T
+pub const SIGHUP: usize = 1;
+/// Terminal interrupt signal.
+/// Default action: T
+pub const SIGINT: usize = 2;
+/// Terminal quit signal.
+/// Default action: A
+pub const SIGQUIT: usize = 3;
+/// Illegal instruction.
+/// Default action: A
+pub const SIGILL: usize = 4;
+/// Trace/Breakpoint trap.
+/// Default action: A
+pub const SIGTRAP: usize = 5;
+/// Process abort signal.
+/// Default action: A
+pub const SIGABRT: usize = 6;
+/// Access to an undefined portion of a memory object.
+/// Default action: A
+pub const SIGBUS: usize = 7;
+/// Erroneous arithmetic operation.
+/// Default action: A
+pub const SIGFPE: usize = 8;
+/// Kill (cannot be caught or ignored).
+/// Default action: T
+pub const SIGKILL: usize = 9;
+/// User-defined signal 1.
+/// Default action: T
+pub const SIGUSR1: usize = 10;
+/// Invalid memory reference.
+/// Default action: A
+pub const SIGSEGV: usize = 11;
+/// User-defined signal 2.
+/// Default action: T
+pub const SIGUSR2: usize = 12;
+/// Write on a pipe with no one to read it.
+/// Default action: T
+pub const SIGPIPE: usize = 13;
+/// Alarm clock.
+/// Default action: T
+pub const SIGALRM: usize = 14;
+/// Termination signal.
+/// Default action: T
+pub const SIGTERM: usize = 15;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/signal.7.html>.
+///
+/// Stack fault on coprocessor (unused).
+pub const SIGSTKFLT: usize = 16;
+/// Child process terminated, stopped or continued.
+/// Default action: I
+pub const SIGCHLD: usize = 17;
+/// Continue executing, if stopped.
+/// Default action: C
+pub const SIGCONT: usize = 18;
+/// Stop executing (cannot be caught or ignored).
+/// Default action: S
+pub const SIGSTOP: usize = 19;
+/// Terminal stop signal.
+/// Default action: S
+pub const SIGTSTP: usize = 20;
+/// Background process attempting read.
+/// Default action: S
+pub const SIGTTIN: usize = 21;
+/// Background process attempting write.
+/// Default action: S
+pub const SIGTTOU: usize = 22;
+/// High bandwidth data is available at a socket.
+/// Default action: I
+pub const SIGURG: usize = 23;
+/// CPU time limit exceeded.
+/// Default action: A
+pub const SIGXCPU: usize = 24;
+/// File size limit exceeded.
+/// Default action: A
+pub const SIGXFSZ: usize = 25;
+/// Virtual timer expired.
+/// Default action: T
+pub const SIGVTALRM: usize = 26;
+// TODO mark #[deprecated]?
+/// Obsolete in issue 7, removed in issue 8.
+///
+/// Profiling timer expired.
+/// Default action: T
+pub const SIGPROF: usize = 27;
+/// Terminal window size changed.
+/// Default action: I
+pub const SIGWINCH: usize = 28;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/signal.7.html>.
+///
+/// I/O now possible (4.2BSD).
+pub const SIGIO: usize = 29;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/signal.7.html>.
+///
+/// Power failure (System V).
+pub const SIGPWR: usize = 30;
+/// Bad system call.
+/// Default action: A
+pub const SIGSYS: usize = 31;
+// TODO add `NSIG_MAX` to limits.h and `_SC_NSIG` to unistd.h sysconf
+/// Non-POSIX.
+///
+/// Intended to define the maximum number of signals supported by this
+/// implemenatation.
+///
+/// POSIX added `NSIG_MAX` as a portable replacement based on the size of the
+/// `sigset_t` type.
+pub const NSIG: usize = 32;
+
+/// Lower bound (inclusive) of the range of signal numbers reserved for
+/// application use and for realtime signals.
+pub const SIGRTMIN: usize = 35; // TODO: decrease to 34
+/// Upper bound (inclusive) of the range of signal numbers reserved for
+/// application use and for realtime signals.
+pub const SIGRTMAX: usize = 64;
+
+/// Causes implementations not to create zombie processes or status information
+/// on child termination. See `sigaction()`.
+pub const SA_NOCLDWAIT: usize = 2;
+
+/// Process is executing on an alternate signal stack.
+pub const SS_ONSTACK: usize = 1;
+/// Alternate signal stack is disabled.
+pub const SS_DISABLE: usize = 2;
+
+// Redox note: should include both SigStack size, and some extra room for the libc handler
+// Linux note: Those two should be updated from kernel headers
+/// Minimum stack size for a signal handler.
+pub const MINSIGSTKSZ: usize = 2048;
+/// Default size in bytes for the alternate signal stack.
+pub const SIGSTKSZ: usize = 8096;
+
+/// Signal sent by `sigqueue()`.
+pub const SI_QUEUE: i32 = -1;
+/// Signal sent by `kill()`.
+pub const SI_USER: i32 = 0;
+/// Signal generated by expiration of a timer set by `timer_settime()`.
+pub const SI_TIMER: i32 = 1;
+/// Signal generated by completion of an asynchronous I/O request.
+pub const SI_ASYNCIO: i32 = 2;
+/// Signal generated by arrival of a message on an empty message queue.
+pub const SI_MESGQ: i32 = 3;
+
+// si_code values (signal-specific)
+/// Illegal opcode.
+pub const ILL_ILLOPC: i32 = 1;
+/// Illegal operand.
+pub const ILL_ILLOPN: i32 = 2;
+/// Illegal addressing mode.
+pub const ILL_ILLADR: i32 = 3;
+/// Illegal trap.
+pub const ILL_ILLTRP: i32 = 4;
+/// Privileged opcode.
+pub const ILL_PRVOPC: i32 = 5;
+/// Privileged register.
+pub const ILL_PRVREG: i32 = 6;
+/// Coprocessor error.
+pub const ILL_COPROC: i32 = 7;
+/// Internal stack error.
+pub const ILL_BADSTK: i32 = 8;
+
+/// Integer divide by zero.
+pub const FPE_INTDIV: i32 = 1;
+/// Integer overflow.
+pub const FPE_INTOVF: i32 = 2;
+/// Floating-point divide by zero.
+pub const FPE_FLTDIV: i32 = 3;
+/// Floating-point overflow.
+pub const FPE_FLTOVF: i32 = 4;
+/// Floating-point underflow.
+pub const FPE_FLTUND: i32 = 5;
+/// Floating-point inexact result.
+pub const FPE_FLTRES: i32 = 6;
+/// Invalid floating-point operation.
+pub const FPE_FLTINV: i32 = 7;
+/// Subscript out of range.
+pub const FPE_FLTSUB: i32 = 8;
+
+/// Address not mapped to object.
+pub const SEGV_MAPERR: i32 = 1;
+/// Invalid permissions for mapped object.
+pub const SEGV_ACCERR: i32 = 2;
+
+/// Invalid address alignment.
+pub const BUS_ADRALN: i32 = 1;
+/// Nonexistent physical address.
+pub const BUS_ADRERR: i32 = 2;
+/// Object-specific hardware error.
+pub const BUS_OBJERR: i32 = 3;
+
+/// Process breakpoint.
+pub const TRAP_BRKPT: i32 = 1;
+/// Process trace trap.
+pub const TRAP_TRACE: i32 = 2;
+
+/// Child has exited.
+pub const CLD_EXITED: i32 = 1;
+/// Child has terminated abnormally with no additional actions.
+pub const CLD_KILLED: i32 = 2;
+/// Child has terminated abnormally and additional actions may have been taken.
+pub const CLD_DUMPED: i32 = 3;
+/// Traced child has trapped.
+pub const CLD_TRAPPED: i32 = 4;
+/// Child has stopped.
+pub const CLD_STOPPED: i32 = 5;
+/// Stopped child has continued.
+pub const CLD_CONTINUED: i32 = 6;
diff --git a/src/header/signal/linux.rs b/src/header/signal/linux.rs
index e933e3054a..1aa9e578d2 100644
--- a/src/header/signal/linux.rs
+++ b/src/header/signal/linux.rs
@@ -34,47 +34,23 @@ global_asm!(
 "
 );
 
-pub const SIGHUP: usize = 1;
-pub const SIGINT: usize = 2;
-pub const SIGQUIT: usize = 3;
-pub const SIGILL: usize = 4;
-pub const SIGTRAP: usize = 5;
-pub const SIGABRT: usize = 6;
-pub const SIGIOT: usize = SIGABRT;
-pub const SIGBUS: usize = 7;
-pub const SIGFPE: usize = 8;
-pub const SIGKILL: usize = 9;
-pub const SIGUSR1: usize = 10;
-pub const SIGSEGV: usize = 11;
-pub const SIGUSR2: usize = 12;
-pub const SIGPIPE: usize = 13;
-pub const SIGALRM: usize = 14;
-pub const SIGTERM: usize = 15;
-pub const SIGSTKFLT: usize = 16;
-pub const SIGCHLD: usize = 17;
-pub const SIGCONT: usize = 18;
-pub const SIGSTOP: usize = 19;
-pub const SIGTSTP: usize = 20;
-pub const SIGTTIN: usize = 21;
-pub const SIGTTOU: usize = 22;
-pub const SIGURG: usize = 23;
-pub const SIGXCPU: usize = 24;
-pub const SIGXFSZ: usize = 25;
-pub const SIGVTALRM: usize = 26;
-pub const SIGPROF: usize = 27;
-pub const SIGWINCH: usize = 28;
-pub const SIGIO: usize = 29;
-pub const SIGPOLL: usize = SIGIO;
-pub const SIGPWR: usize = 30;
-pub const SIGSYS: usize = 31;
-pub const SIGUNUSED: usize = SIGSYS;
-pub const NSIG: usize = 32;
-
-pub const SIGRTMIN: usize = 35; // TODO: decrease to 34
-pub const SIGRTMAX: usize = 64;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/signal.7.html>.
+///
+/// IOT trap. A synonym for `SIGABRT`.
+pub const SIGIOT: usize = super::constants::SIGABRT;
+// TODO mark #[deprecated]?
+/// Obsolete in issue 7, removed in issue 8.
+///
+/// Pollable event.
+/// Default action: T
+pub const SIGPOLL: usize = super::constants::SIGIO;
+/// Non-POSIX, see <https://www.man7.org/linux/man-pages/man7/signal.7.html>.
+///
+/// Synonymous with `SIGSYS`.
+pub const SIGUNUSED: usize = super::constants::SIGSYS;
 
+// TODO why are these SA_* constants different to Redox?
 pub const SA_NOCLDSTOP: usize = 1;
-pub const SA_NOCLDWAIT: usize = 2;
 pub const SA_SIGINFO: usize = 4;
 pub const SA_ONSTACK: usize = 0x0800_0000;
 pub const SA_RESTART: usize = 0x1000_0000;
@@ -82,55 +58,6 @@ pub const SA_NODEFER: usize = 0x4000_0000;
 pub const SA_RESETHAND: usize = 0x8000_0000;
 pub const SA_RESTORER: usize = 0x0400_0000;
 
-pub const SS_ONSTACK: usize = 1;
-pub const SS_DISABLE: usize = 2;
-
-// Those two should be updated from kernel headers
-pub const MINSIGSTKSZ: usize = 2048;
-pub const SIGSTKSZ: usize = 8096;
-
-pub const SI_QUEUE: i32 = -1;
-pub const SI_USER: i32 = 0;
-pub const SI_TIMER: i32 = 1;
-pub const SI_ASYNCIO: i32 = 2;
-pub const SI_MESGQ: i32 = 3;
-
-// si_code values (signal-specific)
-pub const ILL_ILLOPC: i32 = 1;
-pub const ILL_ILLOPN: i32 = 2;
-pub const ILL_ILLADR: i32 = 3;
-pub const ILL_ILLTRP: i32 = 4;
-pub const ILL_PRVOPC: i32 = 5;
-pub const ILL_PRVREG: i32 = 6;
-pub const ILL_COPROC: i32 = 7;
-pub const ILL_BADSTK: i32 = 8;
-
-pub const FPE_INTDIV: i32 = 1;
-pub const FPE_INTOVF: i32 = 2;
-pub const FPE_FLTDIV: i32 = 3;
-pub const FPE_FLTOVF: i32 = 4;
-pub const FPE_FLTUND: i32 = 5;
-pub const FPE_FLTRES: i32 = 6;
-pub const FPE_FLTINV: i32 = 7;
-pub const FPE_FLTSUB: i32 = 8;
-
-pub const SEGV_MAPERR: i32 = 1;
-pub const SEGV_ACCERR: i32 = 2;
-
-pub const BUS_ADRALN: i32 = 1;
-pub const BUS_ADRERR: i32 = 2;
-pub const BUS_OBJERR: i32 = 3;
-
-pub const TRAP_BRKPT: i32 = 1;
-pub const TRAP_TRACE: i32 = 2;
-
-pub const CLD_EXITED: i32 = 1;
-pub const CLD_KILLED: i32 = 2;
-pub const CLD_DUMPED: i32 = 3;
-pub const CLD_TRAPPED: i32 = 4;
-pub const CLD_STOPPED: i32 = 5;
-pub const CLD_CONTINUED: i32 = 6;
-
 // Mirrors the ucontext_t struct from the libc crate on Linux.
 
 pub(crate) type ucontext_t = ucontext;
diff --git a/src/header/signal/mod.rs b/src/header/signal/mod.rs
index b429a2a443..6f537e7401 100644
--- a/src/header/signal/mod.rs
+++ b/src/header/signal/mod.rs
@@ -17,7 +17,9 @@ use crate::{
     },
 };
 
+pub mod constants;
 pub use self::sys::*;
+pub use constants::*;
 
 use super::{
     errno::EFAULT,
diff --git a/src/header/signal/redox.rs b/src/header/signal/redox.rs
index 8d3fd8ba29..5378eca4bb 100644
--- a/src/header/signal/redox.rs
+++ b/src/header/signal/redox.rs
@@ -6,43 +6,7 @@ use crate::platform::types::{c_uint, c_ulong};
 
 use super::{siginfo_t, sigset_t, stack_t};
 
-pub const SIGHUP: usize = 1;
-pub const SIGINT: usize = 2;
-pub const SIGQUIT: usize = 3;
-pub const SIGILL: usize = 4;
-pub const SIGTRAP: usize = 5;
-pub const SIGABRT: usize = 6;
-pub const SIGBUS: usize = 7;
-pub const SIGFPE: usize = 8;
-pub const SIGKILL: usize = 9;
-pub const SIGUSR1: usize = 10;
-pub const SIGSEGV: usize = 11;
-pub const SIGUSR2: usize = 12;
-pub const SIGPIPE: usize = 13;
-pub const SIGALRM: usize = 14;
-pub const SIGTERM: usize = 15;
-pub const SIGSTKFLT: usize = 16;
-pub const SIGCHLD: usize = 17;
-pub const SIGCONT: usize = 18;
-pub const SIGSTOP: usize = 19;
-pub const SIGTSTP: usize = 20;
-pub const SIGTTIN: usize = 21;
-pub const SIGTTOU: usize = 22;
-pub const SIGURG: usize = 23;
-pub const SIGXCPU: usize = 24;
-pub const SIGXFSZ: usize = 25;
-pub const SIGVTALRM: usize = 26;
-pub const SIGPROF: usize = 27;
-pub const SIGWINCH: usize = 28;
-pub const SIGIO: usize = 29;
-pub const SIGPWR: usize = 30;
-pub const SIGSYS: usize = 31;
-pub const NSIG: usize = 32;
-
-pub const SIGRTMIN: usize = 35;
-pub const SIGRTMAX: usize = 64;
-
-pub const SA_NOCLDWAIT: usize = 0x0000_0002;
+// TODO why are these SA_* constants different to Linux?
 pub const SA_RESTORER: usize = 0x0000_0004; // TODO: remove
 pub const SA_SIGINFO: usize = 0x0200_0000;
 pub const SA_ONSTACK: usize = 0x0400_0000;
@@ -51,68 +15,18 @@ pub const SA_NODEFER: usize = 0x1000_0000;
 pub const SA_RESETHAND: usize = 0x2000_0000;
 pub const SA_NOCLDSTOP: usize = 0x4000_0000;
 
-pub const SS_ONSTACK: usize = 0x00000001;
-pub const SS_DISABLE: usize = 0x00000002;
-
 const _: () = {
-    if SS_ONSTACK != redox_rt::signal::SS_ONSTACK {
+    if super::constants::SS_ONSTACK != redox_rt::signal::SS_ONSTACK {
         panic!();
     }
-    if SS_DISABLE != redox_rt::signal::SS_DISABLE {
+    if super::constants::SS_DISABLE != redox_rt::signal::SS_DISABLE {
         panic!();
     }
-    if MINSIGSTKSZ != redox_rt::signal::MIN_SIGALTSTACK_SIZE {
+    if super::constants::MINSIGSTKSZ != redox_rt::signal::MIN_SIGALTSTACK_SIZE {
         panic!();
     }
 };
 
-// should include both SigStack size, and some extra room for the libc handler
-pub const MINSIGSTKSZ: usize = 2048;
-
-pub const SIGSTKSZ: usize = 8096;
-
-pub const SI_QUEUE: i32 = -1;
-pub const SI_USER: i32 = 0;
-pub const SI_TIMER: i32 = 1;
-pub const SI_ASYNCIO: i32 = 2;
-pub const SI_MESGQ: i32 = 3;
-
-// si_code values (signal-specific)
-pub const ILL_ILLOPC: i32 = 1;
-pub const ILL_ILLOPN: i32 = 2;
-pub const ILL_ILLADR: i32 = 3;
-pub const ILL_ILLTRP: i32 = 4;
-pub const ILL_PRVOPC: i32 = 5;
-pub const ILL_PRVREG: i32 = 6;
-pub const ILL_COPROC: i32 = 7;
-pub const ILL_BADSTK: i32 = 8;
-
-pub const FPE_INTDIV: i32 = 1;
-pub const FPE_INTOVF: i32 = 2;
-pub const FPE_FLTDIV: i32 = 3;
-pub const FPE_FLTOVF: i32 = 4;
-pub const FPE_FLTUND: i32 = 5;
-pub const FPE_FLTRES: i32 = 6;
-pub const FPE_FLTINV: i32 = 7;
-pub const FPE_FLTSUB: i32 = 8;
-
-pub const SEGV_MAPERR: i32 = 1;
-pub const SEGV_ACCERR: i32 = 2;
-
-pub const BUS_ADRALN: i32 = 1;
-pub const BUS_ADRERR: i32 = 2;
-pub const BUS_OBJERR: i32 = 3;
-
-pub const TRAP_BRKPT: i32 = 1;
-pub const TRAP_TRACE: i32 = 2;
-
-pub const CLD_EXITED: i32 = 1;
-pub const CLD_KILLED: i32 = 2;
-pub const CLD_DUMPED: i32 = 3;
-pub const CLD_TRAPPED: i32 = 4;
-pub const CLD_STOPPED: i32 = 5;
-pub const CLD_CONTINUED: i32 = 6;
-
 pub(crate) type ucontext_t = ucontext;
 pub(crate) type mcontext_t = mcontext;