diff --git a/ereuse_devicehub/resources/device/sync.py b/ereuse_devicehub/resources/device/sync.py
index f5b0aced..7f883ab1 100644
--- a/ereuse_devicehub/resources/device/sync.py
+++ b/ereuse_devicehub/resources/device/sync.py
@@ -55,7 +55,10 @@ class Sync:
         db_device = self.execute_register(device)
         db_components, events = OrderedSet(), OrderedSet()
         if components is not None:  # We have component info (see above)
-            assert isinstance(db_device, Computer)
+            if not isinstance(db_device, Computer):
+                # Until a good reason is given, we synthetically forbid
+                # non-computers with components
+                raise ValidationError('Only computers can have components.')
             blacklist = set()  # type: Set[int]
             not_new_components = set()
             for component in components:
diff --git a/tests/test_snapshot.py b/tests/test_snapshot.py
index 66160a8e..3126c75a 100644
--- a/tests/test_snapshot.py
+++ b/tests/test_snapshot.py
@@ -5,6 +5,7 @@ from uuid import uuid4
 
 import pytest
 from teal.db import UniqueViolation
+from teal.marshmallow import ValidationError
 
 from ereuse_devicehub.client import UserClient
 from ereuse_devicehub.db import db
@@ -281,6 +282,22 @@ def test_snapshot_upload_twice_uuid_error(user: UserClient):
     user.post(pc1, res=Snapshot, status=UniqueViolation)
 
 
+def test_snapshot_component_containing_components(user: UserClient):
+    """There is no reason for components to have components and when
+    this happens it is always an error.
+
+    This test avoids this until an appropriate use-case is presented.
+    """
+    s = file('basic.snapshot')
+    s['device'] = {
+        'type': 'Processor',
+        'serialNumber': 'foo',
+        'manufacturer': 'bar',
+        'model': 'baz'
+    }
+    user.post(s, res=Snapshot, status=ValidationError)
+
+
 def test_erase(user: UserClient):
     """Tests a Snapshot with EraseSectors."""
     s = file('erase-sectors.snapshot')