diff --git a/libc/arch-x86/syscalls/__ptrace.S b/libc/arch-x86/syscalls/__ptrace.S
index f574cf0..157bdd8 100644
--- a/libc/arch-x86/syscalls/__ptrace.S
+++ b/libc/arch-x86/syscalls/__ptrace.S
@@ -1,4 +1,5 @@
 /* autogenerated by gensyscalls.py */
+#include <linux/err.h>
 #include <machine/asm.h>
 #include <sys/linux-syscalls.h>
 
@@ -13,7 +14,7 @@
     mov     32(%esp), %esi
     movl    $__NR_ptrace, %eax
     int     $0x80
-    cmpl    $-129, %eax
+    cmpl    $-MAX_ERRNO, %eax
     jb      1f
     negl    %eax
     pushl   %eax