diff --git a/controle_cotisation/main.py b/controle_cotisation/main.py
index b74759a..2129f4e 100755
--- a/controle_cotisation/main.py
+++ b/controle_cotisation/main.py
@@ -227,7 +227,7 @@ def notify_unpaid(member):
 
     mailheaders = get_file_content_all(MODALITY_MAIL_HEADERS) + "\n"
     mailheaders = mailheaders.replace("NOM_COTISANT", name)
-    mailheaders = mailheaders.replace("NUMERO_MEMBRE", numero)
+    mailheaders = mailheaders.replace("NUMERO_MEMBRE", str(numero))
     mailheaders = mailheaders.replace("MONTANT_COTISATION", amount)
     mailtext = get_file_content_all(MODALITY_MAIL).replace("ANNEE_CIVILE", year)
     mailtext = mailtext.replace("COURRIEL-COTISANT", email)
@@ -249,7 +249,7 @@ def renotify_unpaid(member):
 
     mailtext = get_file_content_all(MODALITY_MAIL) + "\n"
     mailtext = mailtext.replace("NOM_COTISANT", name)
-    mailtext = mailtext.replace("NUMERO_MEMBRE", numero)
+    mailtext = mailtext.replace("NUMERO_MEMBRE", str(numero))
     mailtext = mailtext.replace("MONTANT_COTISATION", amount)
     mailheaders = get_file_content_all(MODALITY_MAIL_HEADERS).replace("ANNEE_CIVILE", year)
     mailheaders = mailheaders.replace("COURRIEL-COTISANT", email)