diff --git a/popmon/visualization/utils.py b/popmon/visualization/utils.py
index 4e66509a..0b5ae45f 100644
--- a/popmon/visualization/utils.py
+++ b/popmon/visualization/utils.py
@@ -373,7 +373,7 @@ def xtick(lab):
             "x": 1,
             "font": {"size": 10},
         },
-        hovermode='x unified'
+        hovermode="x unified",
     )
 
     plot = json.loads(fig.to_json())