diff --git a/app/scodoc/TrivialFormulator.py b/app/scodoc/TrivialFormulator.py
index 23b500393..25442194f 100644
--- a/app/scodoc/TrivialFormulator.py
+++ b/app/scodoc/TrivialFormulator.py
@@ -276,14 +276,24 @@ class TF(object):
                         )
                         ok = 0
                 if typ[:3] == "int" or typ == "float" or typ == "real":
-                    if "min_value" in descr and val < descr["min_value"]:
+                    if (
+                        val != ""
+                        and val != None
+                        and "min_value" in descr
+                        and val < descr["min_value"]
+                    ):
                         msg.append(
                             "La valeur (%d) du champ '%s' est trop petite (min=%s)"
                             % (val, field, descr["min_value"])
                         )
                         ok = 0
 
-                    if "max_value" in descr and val > descr["max_value"]:
+                    if (
+                        val != ""
+                        and val != None
+                        and "max_value" in descr
+                        and val > descr["max_value"]
+                    ):
                         msg.append(
                             "La valeur (%s) du champ '%s' est trop grande (max=%s)"
                             % (val, field, descr["max_value"])