diff --git a/core/admin/mailu/configuration.py b/core/admin/mailu/configuration.py
index d447e570..a4957da1 100644
--- a/core/admin/mailu/configuration.py
+++ b/core/admin/mailu/configuration.py
@@ -165,6 +165,7 @@ class ConfigManager:
             self.config['SESSION_COOKIE_SECURE'] = self.config['TLS_FLAVOR'] != 'notls'
         self.config['SESSION_PERMANENT'] = True
         self.config['SESSION_TIMEOUT'] = int(self.config['SESSION_TIMEOUT'])
+        self.config['SESSION_KEY_BITS'] = int(self.config['SESSION_KEY_BITS'])
         self.config['PERMANENT_SESSION_LIFETIME'] = int(self.config['PERMANENT_SESSION_LIFETIME'])
         self.config['AUTH_RATELIMIT_IP_V4_MASK'] = int(self.config['AUTH_RATELIMIT_IP_V4_MASK'])
         self.config['AUTH_RATELIMIT_IP_V6_MASK'] = int(self.config['AUTH_RATELIMIT_IP_V6_MASK'])