diff --git a/camdetect.py b/camdetect.py
index 5069f10..d89f480 100755
--- a/camdetect.py
+++ b/camdetect.py
@@ -17,6 +17,7 @@ from jpeg2dct.numpy import loads
 from math import inf
 from motor.motor_asyncio import AsyncIOMotorClient
 from prometheus_client import Counter, Gauge, Histogram
+from pymongo import ReturnDocument
 from sanic import Sanic, response
 from sanic_json_logging import setup_json_logging
 from sanic.log import logger
@@ -256,17 +257,24 @@ async def motion_detector(reference_frame, download_queue, upload_queue):
 
         # Handle event start
         if motion_detected and not event_id:
-            result = await app.ctx.coll.insert_one({
-                "timestamp": dt,
-                "event": "motion-detected",
-                "started": dt,
-                "finished": dt + timedelta(minutes=2),
-                "component": "camdetect",
-                "source": SOURCE_NAME,
-                "screenshots": [],
-                "action": "event",
-            })
-            app.ctx.event_id = event_id = result.inserted_id
+            result = await app.ctx.coll.find_one_and_update({
+                    "timestamp": dt, # TODO: Account for clock skew
+                    "source": SOURCE_NAME,
+                }, {
+                    "$setOnInsert": {
+                        "timestamp": dt,
+                        "source": SOURCE_NAME,
+                        "event": "motion-detected",
+                        "started": dt,
+                        "finished": dt + timedelta(minutes=2),
+                        "component": "camdetect",
+                        "screenshots": [],
+                        "action": "event",
+                    }
+                },
+                upsert = True,
+                return_document=ReturnDocument.AFTER)
+            app.ctx.event_id = event_id = result["_id"]
 
         # Handle buffering frames prior event start
         if hold_queue.full():
@@ -507,6 +515,9 @@ def handler(signum, frame):
 async def setup_db(app, loop):
     app.ctx.db = AsyncIOMotorClient(MONGO_URI).get_default_database()
     app.ctx.coll = app.ctx.db[MONGO_COLLECTION]
+    app.ctx.coll.create_index([
+        ("timestamp", pymongo.ASCENDING),
+        ("source", pymongo.ASCENDING)], unique=True)
     app.ctx.last_frame = None
     app.ctx.event_frame = asyncio.Event()
     app.ctx.event_id = None