diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2
index a3b8f737d..504f61d4b 100644
--- a/man2/ioctl_userfaultfd.2
+++ b/man2/ioctl_userfaultfd.2
@@ -31,6 +31,7 @@ ioctl_userfaultfd \- create a file descriptor for handling page faults in user
 space
 .SH SYNOPSIS
 .nf
+.BR "#include <linux/userfaultfd.h>" "  /* Definition of " UFFD* " constants */"
 .B #include <sys/ioctl.h>
 .PP
 .BI "int ioctl(int " fd ", int " cmd ", ...);"