diff --git a/libc/arch-x86/syscalls/dup2.S b/libc/arch-x86/syscalls/dup2.S
index 43def66..7558f56 100644
--- a/libc/arch-x86/syscalls/dup2.S
+++ b/libc/arch-x86/syscalls/dup2.S
@@ -1,4 +1,5 @@
 /* autogenerated by gensyscalls.py */
+#include <linux/err.h>
 #include <machine/asm.h>
 #include <sys/linux-syscalls.h>
 
@@ -9,7 +10,7 @@
     mov     16(%esp), %ecx
     movl    $__NR_dup2, %eax
     int     $0x80
-    cmpl    $-129, %eax
+    cmpl    $-MAX_ERRNO, %eax
     jb      1f
     negl    %eax
     pushl   %eax