diff --git a/gregui/api/serializers/guest.py b/gregui/api/serializers/guest.py
index 6d93031f9e39ca4eff56d0d458f43df7a10a866e..d22c2e1e524ffca684568047c86a939935f52d80 100644
--- a/gregui/api/serializers/guest.py
+++ b/gregui/api/serializers/guest.py
@@ -61,17 +61,19 @@ class GuestRegisterSerializer(serializers.ModelSerializer):
 
         return instance
 
-    def validate_date_of_birth(self, value):
+    def validate_date_of_birth(self, date_of_birth):
         today = datetime.date.today()
 
         # Check that the date of birth is between the interval starting about 100 years ago and last year
         if (
             not today - datetime.timedelta(weeks=100 * 52)
-            < value
-            < today - datetime.timedelta(weeks=52)
+                < date_of_birth
+                < today - datetime.timedelta(weeks=52)
         ):
             raise serializers.ValidationError("Invalid date of birth")
 
+        return date_of_birth
+
     class Meta:
         model = Person
         fields = (