diff --git a/src/membership/forms.py b/src/membership/forms.py
index cf92d96..c685344 100644
--- a/src/membership/forms.py
+++ b/src/membership/forms.py
@@ -49,10 +49,12 @@ class MembershipForm(forms.ModelForm):
                 self.add_error(fieldname, errormsg)
         if membership and cleaned_data.get('birthday'):
             birthday = cleaned_data.get('birthday')
-            print("Today:", date.today())
-            print("Birthday:", birthday)
-            if date.today().year - cleaned_data.get('birthday').year < 16:
-                self.add_error('birthday', 'Midestalter für Mitlieder ist 16 Jahre!')
+            today = date.today()
+            age = today.year - birthday.year - (
+                    (today.month, today.day) < (birthday.month, birthday.day))
+            if age < 16:
+                self.add_error('birthday',
+                               'Midestalter für Mitlieder ist 16 Jahre!')
 
 
 class RegistrationForm(MembershipForm):