diff --git a/server/camera_endpoint.py b/server/camera_endpoint.py
index d5ebe62..8bababb 100644
--- a/server/camera_endpoint.py
+++ b/server/camera_endpoint.py
@@ -11,14 +11,14 @@ import sqlite3
 from typing import List
 
 from fastapi import Depends
-from pydantic import BaseModel
+from pydantic import BaseModel, Field
 
 
 class CameraRecord(BaseModel):
     period_start: int
     period_end: int
-    entries: int
-    exits: int
+    entries: int = Field(ge=0)
+    exits: int = Field(ge=0)
 
 
 class CameraEventsRequest(BaseModel):
diff --git a/server/test_camera_endpoint.py b/server/test_camera_endpoint.py
index 159fbc7..3917b75 100644
--- a/server/test_camera_endpoint.py
+++ b/server/test_camera_endpoint.py
@@ -89,3 +89,12 @@ def test_entries_exits_stored_correctly():
     assert row[0] == 42
     assert row[1] == 39
     assert row[2] == "retailer-123"
+
+
+def test_negative_counts_rejected():
+    """Pydantic should reject negative entries/exits."""
+    from pydantic import ValidationError
+    from server.camera_endpoint import CameraRecord
+    with pytest.raises(ValidationError):
+        CameraRecord(period_start=1712000000, period_end=1712003600,
+                     entries=-1, exits=0)