diff --git a/libc/arch-x86/syscalls/dup.S b/libc/arch-x86/syscalls/dup.S
index 80259fe..b3de1fb 100644
--- a/libc/arch-x86/syscalls/dup.S
+++ b/libc/arch-x86/syscalls/dup.S
@@ -1,4 +1,5 @@
 /* autogenerated by gensyscalls.py */
+#include <linux/err.h>
 #include <machine/asm.h>
 #include <sys/linux-syscalls.h>
 
@@ -7,7 +8,7 @@
     mov     8(%esp), %ebx
     movl    $__NR_dup, %eax
     int     $0x80
-    cmpl    $-129, %eax
+    cmpl    $-MAX_ERRNO, %eax
     jb      1f
     negl    %eax
     pushl   %eax