diff --git a/otpauth/serializer.py b/otpauth/serializer.py
index 21edb8f..2b7e74e 100644
--- a/otpauth/serializer.py
+++ b/otpauth/serializer.py
@@ -1,8 +1,11 @@
+import logging
 import pyotp
 import otpauth
 from rest_framework import serializers, exceptions
 from otpauth.models import OTPSeed
 
+logger = logging.getLogger(__name__)
+
 # For accessing / modifying the data -- currently unused
 class OTPSerializer(serializers.ModelSerializer):
     class Meta:
@@ -32,21 +35,30 @@ class TokenSerializer(serializers.Serializer):
 
         # only 2 special realms can login
         if not auth_realm in ["ungleich-admin", "ungleich-auth" ]:
+            logger.error("Auth-realm is neither ungleich-admin "
+                         "nor ungleich-auth".format()
+            )
             raise exceptions.AuthenticationFailed()
 
-        print("auth: [{}]{}@'{}' {} + {})".format(self.name_name, auth_name, auth_realm, auth_token, self.validated_data))
+        logger.debug("auth: [{}]{}@'{}' {} + {})".format(
+            self.name_name, auth_name, auth_realm,
+            auth_token, self.validated_data
+        ))
 
         # 1. Verify that the connection might authenticate
         try:
             db_instance = otpauth.models.OTPSeed.objects.get(name=auth_name, realm=auth_realm)
         except (OTPSeed.MultipleObjectsReturned, OTPSeed.DoesNotExist):
-            print("does not exist")
+            logger.error("OTPSeed name: {}, realm: {} does not exist".format(
+                auth_name, auth_realm
+            ))
             raise exceptions.AuthenticationFailed()
 
         totp = pyotp.TOTP(db_instance.seed)
-        print("calculated token = {}".format(totp.now()))
+        logger.debug("calculated token = {}".format(totp.now()))
 
         if not totp.verify(auth_token, valid_window=3):
+            logger.error("totp not verified")
             raise exceptions.AuthenticationFailed()
 
         return (db_instance, auth_token)
@@ -65,6 +77,7 @@ class VerifySerializer(TokenSerializer):
         auth_realm = self.validated_data.get("auth_realm")
 
         if not auth_realm == "ungleich-auth":
+            logger.error("Auth-realm is not ungleich-auth")
             raise exceptions.AuthenticationFailed()
 
         # Do the authentication part