diff --git a/libc/arch-x86/syscalls/dup.S b/libc/arch-x86/syscalls/dup.S
index 0fd9cce..637cfae 100644
--- a/libc/arch-x86/syscalls/dup.S
+++ b/libc/arch-x86/syscalls/dup.S
@@ -6,9 +6,17 @@
     pushl   %ebx
     .cfi_def_cfa_offset 8
     .cfi_rel_offset ebx, 0
-    mov     8(%esp), %ebx
+
+    call    __kernel_syscall
+    pushl   %eax
+    .cfi_adjust_cfa_offset 4
+    .cfi_rel_offset eax, 0
+
+    mov     12(%esp), %ebx
     movl    $__NR_dup, %eax
-    int     $0x80
+    call    *(%esp)
+    addl    $4, %esp
+
     cmpl    $-MAX_ERRNO, %eax
     jb      1f
     negl    %eax