diff --git a/man2/signalfd.2 b/man2/signalfd.2
index d114f1665..3fb14111b 100644
--- a/man2/signalfd.2
+++ b/man2/signalfd.2
@@ -189,6 +189,8 @@ struct signalfd_siginfo {
     uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
     uint64_t ssi_addr;    /* Address that generated signal
                              (for hardware-generated signals) */
+.\" FIXME Since Linux 2.6.37 there is 'uint16_t ssi_addr_lsb'
+.\" which is not yet documented
     uint8_t  pad[\fIX\fP];      /* Pad size to 128 bytes (allow for
                               additional fields in the future) */
 };