diff --git a/recopytex/dashboard/exam.py b/recopytex/dashboard/exam.py
index 30863e5..ff001e2 100644
--- a/recopytex/dashboard/exam.py
+++ b/recopytex/dashboard/exam.py
@@ -293,11 +293,11 @@ def update_competence_fig(data):
         pt.loc[(str(i), "", ""), :] = ""
     pt.sort_index(inplace=True)
     index = (
-        pt.index.get_level_values(0)
+        pt.index.get_level_values(0).map(str)
         + ":"
-        + pt.index.get_level_values(1)
+        + pt.index.get_level_values(1).map(str)
         + " "
-        + pt.index.get_level_values(2)
+        + pt.index.get_level_values(2).map(str)
     )
 
     fig = go.Figure()