diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e0e9fe6
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+cube/build/
diff --git a/readme.md b/readme.md
index e145f98..4c8cb7f 100644
--- a/readme.md
+++ b/readme.md
@@ -8,7 +8,7 @@ On Ubuntu/Debian install
 
 Alternatively use a prepared Docker image
 
-    docker run -it --rm -v ${PWD}:/mnt wollud1969/build-env-arm-none-eabi:1.0.0 bash
+    docker run -it --rm -u ${UID} -v ${PWD}:/mnt wollud1969/build-env-arm-none-eabi:1.0.0 bash
 
 Start the container from the project root.