diff --git a/authentik/stages/authenticator_mobile/api/device.py b/authentik/stages/authenticator_mobile/api/device.py
index c54d935d4..adc92487e 100644
--- a/authentik/stages/authenticator_mobile/api/device.py
+++ b/authentik/stages/authenticator_mobile/api/device.py
@@ -29,10 +29,14 @@ class MobileDeviceSerializer(ModelSerializer):
 
 
 class MobileDeviceEnrollmentSerializer(PassiveSerializer):
+    """Enrollment request, send the device's unique identifier"""
+
     device_uid = CharField(required=True)
 
 
 class MobileDeviceSetPushKeySerializer(PassiveSerializer):
+    """Set notification key"""
+
     firebase_key = CharField(required=True)
 
 
diff --git a/authentik/stages/authenticator_mobile/stage.py b/authentik/stages/authenticator_mobile/stage.py
index 3e9da05db..e85cd0c9c 100644
--- a/authentik/stages/authenticator_mobile/stage.py
+++ b/authentik/stages/authenticator_mobile/stage.py
@@ -62,7 +62,7 @@ class AuthenticatorMobileStageView(ChallengeStageView):
             data={
                 # TODO: use cloud gateway?
                 "u": self.request.build_absolute_uri("/"),
-                "s": self.executor.plan.context[FLOW_PLAN_MOBILE_ENROLL].device.pk,
+                "s": str(self.executor.plan.context[FLOW_PLAN_MOBILE_ENROLL].device.pk),
                 "t": self.executor.plan.context[FLOW_PLAN_MOBILE_ENROLL].token,
             }
         )
diff --git a/schema.yml b/schema.yml
index 4e576240a..79b072cad 100644
--- a/schema.yml
+++ b/schema.yml
@@ -2272,7 +2272,11 @@ paths:
       - mobile_device_token: []
       responses:
         '204':
-          description: No response body
+          content:
+            application/json:
+              schema:
+                type: string
+          description: ''
         '400':
           content:
             application/json:
@@ -35224,6 +35228,7 @@ components:
       - token
     MobileDeviceEnrollmentRequest:
       type: object
+      description: Enrollment request, send the device's unique identifier
       properties:
         device_uid:
           type: string
@@ -35247,6 +35252,7 @@ components:
       - name
     MobileDeviceSetPushKeyRequest:
       type: object
+      description: Set notification key
       properties:
         firebase_key:
           type: string