diff --git a/README.md b/README.md
index 9e83934..1412d96 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,12 @@ bootstrap file :
 dotinstall uninstall bootstrap
 ```
 
+Or update with `update` even in git mode
+
+```
+dotinstall update bootstrap
+```
+
 ## Boostrap file syntax
 
 `bootstrap` is a simple bash script sourced by `dotinstall`. The `bootstrap`
@@ -128,6 +134,23 @@ define_env "NOTMUCH_CONFIG" "~/.config/notmuch"
      displayed.
  - `OVERWRITE_FILE` : do the same with file
 
+## Return code
+
+This script return 0 if there is not error.
+
+ - **1** : no bootstrap specified.
+ - **2** : boostrap file not found
+
+### Git relative error codes
+
+ - **20** : can't clone dotfile git repository.
+ - **24** : can't update dotfile git repository.
+ - **25** : local git repository does not exist.
+
+### Script relative error code
+
+ - **128** : a binary checked by `chek_bin()` is not present
+
 ## Licence
 
 This software is licenced under the GNU-GPL 3 licence, you can found a copy of
diff --git a/src/dotinstall.sh b/src/dotinstall.sh
index 84cbde0..9469260 100755
--- a/src/dotinstall.sh
+++ b/src/dotinstall.sh
@@ -342,7 +342,7 @@ case $1 in
         ;;
 esac
 
-[ "$*" = "" ] && die "You must specify a bootstrap file or repo" 10 1
+[ "$*" = "" ] && die "You must specify a bootstrap file or repo" 1 1
 
 if [[ $* =~ ^https://.*\.git$ || $* =~ ^ssh://.*\.git$ ]]
 then
@@ -364,7 +364,7 @@ else
     bootstrap_file="$*"
 fi
 
-[ ! -f "$bootstrap_file" ] && die "$bootstrap_file does not exist" 10 1
+[ ! -f "$bootstrap_file" ] && die "$bootstrap_file does not exist" 2 1
 
 private:get_bootstrap_path "$bootstrap_file"