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