diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index baac5d0..935639e 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -33,7 +33,7 @@
 void    _exit_thread:exit (int)	    1
 pid_t   __fork:fork (void)           2
 pid_t   _waitpid:waitpid (pid_t, int*, int, struct rusage*)   -1,7
-int     waitid(int, pid_t, struct siginfo_t*, int,void*)          280,284
+int     __waitid:waitid(int, pid_t, struct siginfo_t*, int,void*)          280,284
 
 # NOTE: this system call is never called directly, but we list it there
 #       to have __NR_clone properly defined.
diff --git a/libc/arch-arm/syscalls.mk b/libc/arch-arm/syscalls.mk
index f1d8fb1..c364d1c 100644
--- a/libc/arch-arm/syscalls.mk
+++ b/libc/arch-arm/syscalls.mk
@@ -3,7 +3,7 @@
 syscall_src += arch-arm/syscalls/_exit.S
 syscall_src += arch-arm/syscalls/_exit_thread.S
 syscall_src += arch-arm/syscalls/__fork.S
-syscall_src += arch-arm/syscalls/waitid.S
+syscall_src += arch-arm/syscalls/__waitid.S
 syscall_src += arch-arm/syscalls/__sys_clone.S
 syscall_src += arch-arm/syscalls/execve.S
 syscall_src += arch-arm/syscalls/__setuid.S
diff --git a/libc/arch-arm/syscalls/waitid.S b/libc/arch-arm/syscalls/__waitid.S
similarity index 86%
rename from libc/arch-arm/syscalls/waitid.S
rename to libc/arch-arm/syscalls/__waitid.S
index 4134e53..fdd0da3 100644
--- a/libc/arch-arm/syscalls/waitid.S
+++ b/libc/arch-arm/syscalls/__waitid.S
@@ -2,12 +2,12 @@
 #include <sys/linux-syscalls.h>
 
     .text
-    .type waitid, #function
-    .globl waitid
+    .type __waitid, #function
+    .globl __waitid
     .align 4
     .fnstart
 
-waitid:
+__waitid:
     mov     ip, sp
     .save   {r4, r5, r6, r7}
     stmfd   sp!, {r4, r5, r6, r7}
diff --git a/libc/arch-sh/syscalls.mk b/libc/arch-sh/syscalls.mk
index 3e2274f..47b5a1e 100644
--- a/libc/arch-sh/syscalls.mk
+++ b/libc/arch-sh/syscalls.mk
@@ -4,7 +4,7 @@
 syscall_src += arch-sh/syscalls/_exit_thread.S
 syscall_src += arch-sh/syscalls/__fork.S
 syscall_src += arch-sh/syscalls/_waitpid.S
-syscall_src += arch-sh/syscalls/waitid.S
+syscall_src += arch-sh/syscalls/__waitid.S
 syscall_src += arch-sh/syscalls/__sys_clone.S
 syscall_src += arch-sh/syscalls/execve.S
 syscall_src += arch-sh/syscalls/__setuid.S
diff --git a/libc/arch-sh/syscalls/waitid.S b/libc/arch-sh/syscalls/__waitid.S
similarity index 90%
rename from libc/arch-sh/syscalls/waitid.S
rename to libc/arch-sh/syscalls/__waitid.S
index 1f0432d..1f58de0 100644
--- a/libc/arch-sh/syscalls/waitid.S
+++ b/libc/arch-sh/syscalls/__waitid.S
@@ -2,11 +2,11 @@
 #include <sys/linux-syscalls.h>
 
     .text
-    .type waitid, @function
-    .globl waitid
+    .type __waitid, @function
+    .globl __waitid
     .align 4
 
-waitid:
+__waitid:
 
     /* get ready for additonal arg */
     mov.l   @r15, r0
diff --git a/libc/arch-x86/syscalls.mk b/libc/arch-x86/syscalls.mk
index f0d7a31..133f286 100644
--- a/libc/arch-x86/syscalls.mk
+++ b/libc/arch-x86/syscalls.mk
@@ -4,7 +4,7 @@
 syscall_src += arch-x86/syscalls/_exit_thread.S
 syscall_src += arch-x86/syscalls/__fork.S
 syscall_src += arch-x86/syscalls/_waitpid.S
-syscall_src += arch-x86/syscalls/waitid.S
+syscall_src += arch-x86/syscalls/__waitid.S
 syscall_src += arch-x86/syscalls/__sys_clone.S
 syscall_src += arch-x86/syscalls/execve.S
 syscall_src += arch-x86/syscalls/__setuid.S
diff --git a/libc/arch-x86/syscalls/waitid.S b/libc/arch-x86/syscalls/__waitid.S
similarity index 90%
rename from libc/arch-x86/syscalls/waitid.S
rename to libc/arch-x86/syscalls/__waitid.S
index 9a5328b..4dd8c11 100644
--- a/libc/arch-x86/syscalls/waitid.S
+++ b/libc/arch-x86/syscalls/__waitid.S
@@ -2,11 +2,11 @@
 #include <sys/linux-syscalls.h>
 
     .text
-    .type waitid, @function
-    .globl waitid
+    .type __waitid, @function
+    .globl __waitid
     .align 4
 
-waitid:
+__waitid:
     pushl   %ebx
     pushl   %ecx
     pushl   %edx
diff --git a/libc/include/sys/linux-unistd.h b/libc/include/sys/linux-unistd.h
index 5e9c2f0..a1905b3 100644
--- a/libc/include/sys/linux-unistd.h
+++ b/libc/include/sys/linux-unistd.h
@@ -9,7 +9,7 @@
 void             _exit_thread (int);
 pid_t            __fork (void);
 pid_t            _waitpid (pid_t, int*, int, struct rusage*);
-int              waitid (int, pid_t, struct siginfo_t*, int,void*);
+int              __waitid (int, pid_t, struct siginfo_t*, int,void*);
 pid_t            __sys_clone (int, void*, int*, void*, int*);
 int              execve (const char*, char* const*, char* const*);
 int              __setuid (uid_t);
diff --git a/libc/include/sys/wait.h b/libc/include/sys/wait.h
index 8ba1837..573e220 100644
--- a/libc/include/sys/wait.h
+++ b/libc/include/sys/wait.h
@@ -32,6 +32,7 @@
 #include <sys/types.h>
 #include <sys/resource.h>
 #include <linux/wait.h>
+#include <signal.h>
 
 __BEGIN_DECLS
 
@@ -49,6 +50,14 @@
 extern pid_t  wait3(int *, int, struct rusage *);
 extern pid_t  wait4(pid_t, int *, int, struct rusage *);
 
+/* Posix states that idtype_t should be an enumeration type, but
+ * the kernel headers define P_ALL, P_PID and P_PGID as constant macros
+ * instead.
+ */
+typedef int idtype_t;
+
+extern int  waidit(idtype_t which, id_t id, siginfo_t *info, int options);
+
 __END_DECLS
 
 #endif /* _SYS_WAIT_H_ */
diff --git a/libc/unistd/wait.c b/libc/unistd/wait.c
index d172419..f1db086 100644
--- a/libc/unistd/wait.c
+++ b/libc/unistd/wait.c
@@ -29,6 +29,7 @@
 #include <stddef.h>
 
 extern pid_t  __wait4 (pid_t pid, int *status, int options, struct rusage *rusage);
+extern int    __waitid(idtype_t which, id_t id, siginfo_t *info, int options, struct rusage *ru);
 
 pid_t  wait( int*  status )
 {
@@ -44,3 +45,9 @@
 {
     return __wait4( pid, status, options, NULL );
 }
+
+int  waitid(idtype_t which, id_t id, siginfo_t *info, int options)
+{
+    /* the system call takes an option struct rusage that we don't need */
+    return __waitid(which, id, info, options, NULL);
+}