diff --git a/README.md b/README.md
index 5ea3ee2..2d9efc9 100644
--- a/README.md
+++ b/README.md
@@ -13,11 +13,18 @@
 ### Configuration
 
 By default, Android SDK is expected under `~/android/sdk`.
-It is possible to adapt this path in `docker-compose.yml`.
-But it may also be specified in your `local.properties`!
+It is possible to adapt this path in `local.properties` (not to be committed).
+
 
 ### Usage
 
+If the current user id and group id are not 1000, it is required to define them using environment variables:
+
+```
+export _UID="$(id -u)"
+export _GID="$(id -g)"
+```
+
 The following command should build (if required) and start a shell session inside the container:
 
 ```
diff --git a/lazyDir/centos7.Dockerfile b/lazyDir/centos7.Dockerfile
index 75d1e0d..4099adb 100644
--- a/lazyDir/centos7.Dockerfile
+++ b/lazyDir/centos7.Dockerfile
@@ -127,9 +127,10 @@
 ARG gid=1000
 ARG group=android
 
-# Add user to build
-RUN groupadd -g "${gid}" "${group}" && \
-    useradd -ms /bin/bash -g "${group}" -u "${uid}" "${user}"
+# Add or modify user and group for build and runtime (convenient)
+RUN id ${user} > /dev/null 2>&1 && \
+    { groupmod -g "${gid}" "${group}" && usermod -md /home/${user} -s /bin/bash -g "${group}" -u "${uid}" "${user}"; } || \
+    { groupadd -g "${gid}" "${group}" && useradd -md /home/${user} -s /bin/bash -g "${group}" -u "${uid}" "${user}"; }
 
 # Copy requirements in non-root user home directory
 COPY Gemfile Gemfile.lock "/home/${user}/"