diff --git a/share/man/man5/device.hints.5 b/share/man/man5/device.hints.5
index 5fd4d70ed1a2..578d278f1ce5 100644
--- a/share/man/man5/device.hints.5
+++ b/share/man/man5/device.hints.5
@@ -93,6 +93,8 @@ The keyword may be:
 specifies a bus to which the device is attached.
 .It Li port
 specifies the start address of I/O ports to be used by the device.
+.It Li portsize
+specifies the number of ports used by the device.
 .It Li irq
 is the interrupt line number to be used.
 .It Li drq