diff --git a/doc/manuals/chapters/running.adoc b/doc/manuals/chapters/running.adoc
index d7e6383..5daecf8 100644
--- a/doc/manuals/chapters/running.adoc
+++ b/doc/manuals/chapters/running.adoc
@@ -6,7 +6,7 @@
 
 === SYNOPSIS
 
-*osmo-pcu* [-h|-V] [-D] [-c 'CONFIGFILE'] [-r 'PRIO'] [-m 'MCC'] [-n 'MNC']
+*osmo-pcu* [-h|-V] [-D] [-c 'CONFIGFILE'] [-r 'PRIO'] [-m 'MCC'] [-n 'MNC'] [-i A.B.C.D]
 
 
 === OPTIONS
@@ -31,3 +31,5 @@
 	Use the given MCC instead of that provided by BTS via PCU socket
 *-n, --mnc 'MNC'*::
 	Use the given MNC instead of that provided by BTS via PCU socket
+*-i, --gsmtap-ip 'A.B.C.D'*::
+        Send Um interface trace via GSMTAP to specified IP address