diff --git a/core/models.py b/core/models.py
index 4fea52c..ddd3baa 100644
--- a/core/models.py
+++ b/core/models.py
@@ -13,3 +13,7 @@ class UserShippingAddress(models.Model):
 
     def __str__(self):
         return self.user.username
+
+
+# Enforce unique email addresses
+User._meta.get_field('email')._unique = True
diff --git a/xmrauctions/settings.py b/xmrauctions/settings.py
index acea3a5..4a4cdc5 100644
--- a/xmrauctions/settings.py
+++ b/xmrauctions/settings.py
@@ -25,7 +25,8 @@ SECRET_KEY = os.environ['SECRET_KEY']
 DEBUG = os.environ.get('DEBUG', False)
 ALLOWED_HOSTS = str(os.environ['ALLOWED_HOSTS']).split(',')
 ESCROW_PERIOD_DAYS = os.environ.get('ESCROW_PERIOD_DAYS', 30)
-PLATFORM_FEE_PERCENT = os.environ.get('PLATFORM_FEE_PERCENT', 6)
+PLATFORM_FEE_PERCENT = os.environ.get('PLATFORM_FEE_PERCENT', 5)
+
 
 # Application definition