diff --git a/src/utils/system.py b/src/utils/system.py
index 71ed49b1d..c608021bd 100644
--- a/src/utils/system.py
+++ b/src/utils/system.py
@@ -29,7 +29,9 @@ YUNOHOST_PACKAGES = ["yunohost", "yunohost-admin", "moulinette", "ssowat"]
 
 
 def debian_version():
-    return check_output('grep "^VERSION_CODENAME=" /etc/os-release 2>/dev/null | cut -d= -f2')
+    return check_output(
+        'grep "^VERSION_CODENAME=" /etc/os-release 2>/dev/null | cut -d= -f2'
+    )
 
 
 def system_arch():