diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 423a24e..ca48cfb 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -79,6 +79,7 @@
 int     prctl(int option, unsigned int arg2, unsigned int arg3, unsigned int arg4, unsigned int arg5)  172
 int     capget(cap_user_header_t header, cap_user_data_t data) 184
 int     capset(cap_user_header_t header, const cap_user_data_t data) 185
+int     sigaltstack(const stack_t*, stack_t*) 186
 int     acct(const char*  filepath)  51
 
 # file descriptors
diff --git a/libc/arch-arm/syscalls.mk b/libc/arch-arm/syscalls.mk
index 96471bf..3020930 100644
--- a/libc/arch-arm/syscalls.mk
+++ b/libc/arch-arm/syscalls.mk
@@ -37,6 +37,7 @@
 syscall_src += arch-arm/syscalls/prctl.S
 syscall_src += arch-arm/syscalls/capget.S
 syscall_src += arch-arm/syscalls/capset.S
+syscall_src += arch-arm/syscalls/sigaltstack.S
 syscall_src += arch-arm/syscalls/acct.S
 syscall_src += arch-arm/syscalls/read.S
 syscall_src += arch-arm/syscalls/write.S
diff --git a/libc/arch-arm/syscalls/sigaltstack.S b/libc/arch-arm/syscalls/sigaltstack.S
new file mode 100644
index 0000000..3625d0b
--- /dev/null
+++ b/libc/arch-arm/syscalls/sigaltstack.S
@@ -0,0 +1,19 @@
+/* autogenerated by gensyscalls.py */
+#include <sys/linux-syscalls.h>
+
+    .text
+    .type sigaltstack, #function
+    .globl sigaltstack
+    .align 4
+    .fnstart
+
+sigaltstack:
+    .save   {r4, r7}
+    stmfd   sp!, {r4, r7}
+    ldr     r7, =__NR_sigaltstack
+    swi     #0
+    ldmfd   sp!, {r4, r7}
+    movs    r0, r0
+    bxpl    lr
+    b       __set_syscall_errno
+    .fnend
diff --git a/libc/arch-sh/syscalls.mk b/libc/arch-sh/syscalls.mk
index ac12ae4..c848954 100644
--- a/libc/arch-sh/syscalls.mk
+++ b/libc/arch-sh/syscalls.mk
@@ -41,6 +41,7 @@
 syscall_src += arch-sh/syscalls/prctl.S
 syscall_src += arch-sh/syscalls/capget.S
 syscall_src += arch-sh/syscalls/capset.S
+syscall_src += arch-sh/syscalls/sigaltstack.S
 syscall_src += arch-sh/syscalls/acct.S
 syscall_src += arch-sh/syscalls/read.S
 syscall_src += arch-sh/syscalls/write.S
diff --git a/libc/arch-sh/syscalls/sigaltstack.S b/libc/arch-sh/syscalls/sigaltstack.S
new file mode 100644
index 0000000..8b03e27
--- /dev/null
+++ b/libc/arch-sh/syscalls/sigaltstack.S
@@ -0,0 +1,32 @@
+/* autogenerated by gensyscalls.py */
+#include <sys/linux-syscalls.h>
+
+    .text
+    .type sigaltstack, @function
+    .globl sigaltstack
+    .align 4
+
+sigaltstack:
+
+    /* invoke trap */
+    mov.l   0f, r3  /* trap num */
+    trapa   #(2 + 0x10)
+
+    /* check return value */
+    cmp/pz  r0
+    bt      __NR_sigaltstack_end
+
+    /* keep error number */
+    sts.l   pr, @-r15
+    mov.l   1f, r1
+    jsr     @r1
+    mov     r0, r4
+    lds.l   @r15+, pr
+
+__NR_sigaltstack_end:
+    rts
+    nop
+
+    .align  2
+0:  .long   __NR_sigaltstack
+1:  .long   __set_syscall_errno
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index dbc55e6..6a528e3 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -40,6 +40,7 @@
 syscall_src += arch-x86/syscalls/prctl.S
 syscall_src += arch-x86/syscalls/capget.S
 syscall_src += arch-x86/syscalls/capset.S
+syscall_src += arch-x86/syscalls/sigaltstack.S
 syscall_src += arch-x86/syscalls/acct.S
 syscall_src += arch-x86/syscalls/read.S
 syscall_src += arch-x86/syscalls/write.S
diff --git a/libc/arch-x86/syscalls/sigaltstack.S b/libc/arch-x86/syscalls/sigaltstack.S
new file mode 100644
index 0000000..d39419d
--- /dev/null
+++ b/libc/arch-x86/syscalls/sigaltstack.S
@@ -0,0 +1,26 @@
+/* autogenerated by gensyscalls.py */
+#include <sys/linux-syscalls.h>
+
+    .text
+    .type sigaltstack, @function
+    .globl sigaltstack
+    .align 4
+
+sigaltstack:
+    pushl   %ebx
+    pushl   %ecx
+    mov     12(%esp), %ebx
+    mov     16(%esp), %ecx
+    movl    $__NR_sigaltstack, %eax
+    int     $0x80
+    cmpl    $-129, %eax
+    jb      1f
+    negl    %eax
+    pushl   %eax
+    call    __set_errno
+    addl    $4, %esp
+    orl     $-1, %eax
+1:
+    popl    %ecx
+    popl    %ebx
+    ret
diff --git a/libc/docs/CHANGES.TXT b/libc/docs/CHANGES.TXT
index 47289f6..d7f54ba 100644
--- a/libc/docs/CHANGES.TXT
+++ b/libc/docs/CHANGES.TXT
@@ -68,6 +68,8 @@
   errno. Previous implementation returned -1 on error, setting errno, which
   is not Posix compliant.
 
+- add sigaltstack() implementation for ARM.
+
 -------------------------------------------------------------------------------
 Differences between Android 2.1 and 2.0.1:
 
diff --git a/libc/include/sys/linux-syscalls.h b/libc/include/sys/linux-syscalls.h
index c4e6e45..30c58fd 100644
--- a/libc/include/sys/linux-syscalls.h
+++ b/libc/include/sys/linux-syscalls.h
@@ -42,6 +42,7 @@
 #define __NR_prctl                        (__NR_SYSCALL_BASE + 172)
 #define __NR_capget                       (__NR_SYSCALL_BASE + 184)
 #define __NR_capset                       (__NR_SYSCALL_BASE + 185)
+#define __NR_sigaltstack                  (__NR_SYSCALL_BASE + 186)
 #define __NR_acct                         (__NR_SYSCALL_BASE + 51)
 #define __NR_read                         (__NR_SYSCALL_BASE + 3)
 #define __NR_write                        (__NR_SYSCALL_BASE + 4)
diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index f48dbcd..d6f706b 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -48,6 +48,7 @@
 int              prctl (int option, unsigned int arg2, unsigned int arg3, unsigned int arg4, unsigned int arg5);
 int              capget (cap_user_header_t header, cap_user_data_t data);
 int              capset (cap_user_header_t header, const cap_user_data_t data);
+int              sigaltstack (const stack_t*, stack_t*);
 int              acct (const char*  filepath);
 ssize_t          read (int, void*, size_t);
 ssize_t          write (int, const void*, size_t);