diff --git a/include/assert.h b/include/assert.h
index 3de837a..583dfac 100644
--- a/include/assert.h
+++ b/include/assert.h
@@ -8,6 +8,6 @@
         } \
     } while(0)
 
-extern _Noreturn void __assert_fail(const char *file, int line, const char *message);
+[[noreturn]] void __assert_fail(const char *file, int line, const char *message);
 
 #endif
diff --git a/include/bits/setjmp.h b/include/bits/setjmp.h
new file mode 100644
index 0000000..6d6e5c8
--- /dev/null
+++ b/include/bits/setjmp.h
@@ -0,0 +1,7 @@
+#ifndef _YGGDRASIL_SETJMP_H
+#define _YGGDRASIL_SETJMP_H 1
+
+int setjmp(jmp_buf env);
+[[noreturn]] void longjmp(jmp_buf env, int val);
+
+#endif
diff --git a/src/header/mod.rs b/src/header/mod.rs
index f629492..5847217 100644
--- a/src/header/mod.rs
+++ b/src/header/mod.rs
@@ -1,5 +1,7 @@
 #![allow(nonstandard_style, unused_variables)]
 
+// TODO limits.h is compiler-provided
+
 pub mod sys_types;
 pub mod sys_wait;
 
@@ -10,6 +12,7 @@ pub mod fcntl;
 pub mod limits;
 pub mod locale;
 pub mod math;
+pub mod setjmp;
 pub mod stdio;
 pub mod stdlib;
 pub mod string;
@@ -43,7 +46,7 @@ NEVER           iso646.h - alternative spellings
 -----           libgen.h - definitions for pattern matching functions
 PARTIAL         limits.h - implementation-defined constants
 -----           locale.h - category macros
------           math.h - mathematical declarations
+-----           math.h - mathematical declarations TODO there're parts of libm in yggdrasil-rt
 -----           monetary.h - monetary types
 NEVER           mqueue.h - message queues (REALTIME)
 NEVER           ndbm.h - definitions for ndbm database operations
diff --git a/src/header/setjmp/cbindgen.toml b/src/header/setjmp/cbindgen.toml
new file mode 100644
index 0000000..ee66b1b
--- /dev/null
+++ b/src/header/setjmp/cbindgen.toml
@@ -0,0 +1,15 @@
+language = "C"
+style = "Type"
+
+sys_includes = ["stdarg.h", "stddef.h"]
+no_includes = true
+
+include_guard = "_SETJMP_H"
+trailer = "#include <bits/setjmp.h>"
+
+usize_type = "size_t"
+isize_type = "ssize_t"
+
+[export]
+include = ["jmp_buf"]
+exclude = []
diff --git a/src/header/setjmp/mod.rs b/src/header/setjmp/mod.rs
new file mode 100644
index 0000000..af8bb3b
--- /dev/null
+++ b/src/header/setjmp/mod.rs
@@ -0,0 +1,7 @@
+use core::ffi::c_int;
+
+#[cfg(target_arch = "x86_64")]
+mod x86_64;
+
+#[cfg(target_arch = "x86_64")]
+pub type jmp_buf = *mut x86_64::__jmp_buf;
diff --git a/src/header/setjmp/x86_64.S b/src/header/setjmp/x86_64.S
new file mode 100644
index 0000000..9858bf0
--- /dev/null
+++ b/src/header/setjmp/x86_64.S
@@ -0,0 +1,46 @@
+.global setjmp
+.global longjmp
+
+.global _setjmp
+.global _longjmp
+
+.section .text
+// args:
+// %rdi -- __jmp_buf *env
+setjmp:
+_setjmp:
+    movq %rbx, 0(%rdi)
+    movq %rbp, 8(%rdi)
+    movq %r12, 16(%rdi)
+    movq %r13, 24(%rdi)
+    movq %r14, 32(%rdi)
+    movq %r15, 40(%rdi)
+    // Calculate return stack and rip
+    leaq 8(%rsp), %rax
+    movq %rax, 48(%rdi)
+    movq (%rsp), %rax
+    movq %rax, 56(%rdi)
+
+    movq $0, %rax
+    ret
+
+// args:
+// %rdi -- __jmp_buf *env
+// %rsi -- int val
+longjmp:
+_longjmp:
+    // Restore registers
+    movq 0(%rdi), %rbx
+    movq 8(%rdi), %rbp
+    movq 16(%rdi), %r12
+    movq 24(%rdi), %r13
+    movq 32(%rdi), %r14
+    movq 40(%rdi), %r15
+    movq 48(%rdi), %rsp
+    movq 56(%rdi), %rax
+    pushq %rax
+
+    // Setup return value
+    movq %rsi, %rax
+
+    ret
diff --git a/src/header/setjmp/x86_64.rs b/src/header/setjmp/x86_64.rs
new file mode 100644
index 0000000..a6d75f7
--- /dev/null
+++ b/src/header/setjmp/x86_64.rs
@@ -0,0 +1,15 @@
+use core::{arch::global_asm, ffi::c_int};
+
+#[repr(C)]
+pub struct __jmp_buf {
+    rip: usize,
+    rsp: usize,
+    r15: usize,
+    r14: usize,
+    r13: usize,
+    r12: usize,
+    rbp: usize,
+    rbx: usize,
+}
+
+global_asm!(include_str!("x86_64.S"), options(att_syntax));