diff --git a/action_map.yml b/action_map.yml
index a1558440..9e55afab 100644
--- a/action_map.yml
+++ b/action_map.yml
@@ -267,11 +267,12 @@ app:
                 -p:
                     full: --path
                     default: "/"
+                    pattern: '^\/([a-zA-Z-_\/\.0-9])*$'
                 -l:
                     full: --label
                 -m:
                     full: --mode
-                    help: level of protectness of the app (public|protected|private)
+                    help: level of privacy of the app (public|protected|private)
                     default: 'private'
 
         ### app_remove() TODO: Write help
diff --git a/yunohost_app.py b/yunohost_app.py
index 32963b3e..6b5b4aed 100644
--- a/yunohost_app.py
+++ b/yunohost_app.py
@@ -159,7 +159,6 @@ def app_install(app, domain, path='/', label=None, mode='private'):
     """
     # TODO: Virer la règle "default" lemon
     # TODO: check path and url_to_(un)protect pattern
-    # TODO: check if app is installed on this domain/path (or subpath)
 
     with YunoHostLDAP() as yldap:
 
@@ -206,6 +205,9 @@ def app_install(app, domain, path='/', label=None, mode='private'):
                 if app_settings['path'] == path:
                     raise YunoHostError(1, _("An app is already installed on this location"))
 
+                if app_settings['path'] in path and app_settings['path'].count('/') < path.count('/'):
+                    raise YunoHostError(1, _("Unable to install app at this location"))
+
         unique_app_id = manifest['yunohost']['uid'] +'__'+ str(instance_number)
         app_final_path = apps_path +'/'+ unique_app_id
         script_var_dict = { 'APP_DIR': app_tmp_folder }