diff --git a/controle_cotisation/main.py b/controle_cotisation/main.py
index 5c74b41..aaac890 100755
--- a/controle_cotisation/main.py
+++ b/controle_cotisation/main.py
@@ -369,6 +369,11 @@ def validate(member):
                                                     str(answer["amount"])[:-2],
                                                     str(answer["amount"])[-2:]))
     latexfile = latexfile.replace("DATE-VERSEMENT", date)
+    
+    if not answer["true_reference"]:
+        BUF.append("Erreur : référence introuvable (déféré)")
+        return
+
     latexfile = latexfile.replace("MODE-VERSEMENT", answer["true_reference"])
 
     try: