diff --git a/Dockerfile b/Dockerfile
index 4b8fd67..e48197a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -5,7 +5,7 @@
 #
 
 # Pull base image.
-FROM jlesage/baseimage-gui:alpine-3.5-v1.2.3
+FROM jlesage/baseimage-gui:alpine-3.5-v1.3.0
 
 # Define variables needed by the build.
 ARG DUPEGURU_VERSION=4.0.3
diff --git a/README.md b/README.md
index 0f09f54..d3b2dbf 100644
--- a/README.md
+++ b/README.md
@@ -65,6 +65,7 @@ of this parameter has the format `<VARIABLE_NAME>=<VALUE>`.
 |`DISPLAY_HEIGHT`| Height (in pixels) of the display.            | 768     |
 |`VNC_PASSWORD`  | Password needed to connect to the application's GUI.  See the [VNC Pasword](#vnc-password) section for more details. | (unset) |
 |`KEEP_GUIAPP_RUNNING`| When set to `1`, the application will be automatically restarted if it crashes or if user quits it. | (unset) |
+|`APP_NICENESS`  | Priority at which the X application should run.  A niceness value of −20 is the highest priority and 19 is the lowest priority.  By default, niceness is not set, meaning that the default niceness of 0 is used.  **NOTE**: A negative niceness (priority increase) usually requires additional permissions.  In this case, the container should be run with the docker option `--cap-add=SYS_NICE`. | (unset) |
 
 [TimeZone]: http://en.wikipedia.org/wiki/List_of_tz_database_time_zones