diff --git a/conf/modules/gps_ubx_ucenter.xml b/conf/modules/gps_ubx_ucenter.xml
index 056d7dc991..1f2880dfad 100644
--- a/conf/modules/gps_ubx_ucenter.xml
+++ b/conf/modules/gps_ubx_ucenter.xml
@@ -3,18 +3,20 @@
 <module name="gps_ubx" dir="gps">
   <doc>
     <description>
-      Ublox GPS autoconfiguration.
+Ublox GPS autoconfiguration.
 
-      Automatically configure any Ublox GPS for paparazzi.
+Automatically configure any Ublox GPS for paparazzi.
 
-      -configures all the messages, and the rates
-      -automatic baudrate detection
+- configures all the messages, and the rates
+- automatic baudrate detection
 
-      Warning: you still need to tell the driver
-      a) which paparazzi uart you use
-      b) inside the ublox gps there are also many ports. the tiny/ppzgps use ublox_internal_port1 but if for instance you use a LS-SAM or I2C device you need to configure:
+Warning: you still need to tell the driver
+1. Which paparazzi uart you use
+2. Inside the ublox gps there are also many ports.
+   The tiny/ppzgps use ublox_internal_port1 (UART1) but if for instance you use a LS-SAM
+   or I2C device you need to set this by defining GPS_PORT_ID.
     </description>
-    <define name="GPS_PORT_ID" value="GPS_PORT_UART2" description=""/>
+    <define name="GPS_PORT_ID" value="GPS_PORT_UART1" description="Port inside the Ublox GPS (GPS_PORT_DDC, GPS_PORT_UART1, GPS_PORT_UART2, GPS_PORT_USB, GPS_PORT_SPI)"/>
   </doc>
   <header>
     <file name="gps_ubx_ucenter.h"/>