diff --git a/scripts/collect_hashtags.py b/scripts/collect_hashtags.py
index be6c80d..71ffdd6 100644
--- a/scripts/collect_hashtags.py
+++ b/scripts/collect_hashtags.py
@@ -4,7 +4,7 @@
 from sseclient import SSEClient as EventSource
 import sys
 
-from common import valid_hashtag, valid_edit, hashtag_match
+from common import valid_hashtag, valid_edit, hashtag_match, is_canary
 import db
 
 import mwapi
@@ -151,6 +151,9 @@ def populate_media_information(change):
         except ValueError:
             continue
 
+        if is_canary(change):
+            continue
+
         if "comment" in change:
             hashtag_matches = hashtag_match(change["comment"])
             if hashtag_matches and valid_edit(change):
diff --git a/scripts/common.py b/scripts/common.py
index 9a0c520..6c739a7 100644
--- a/scripts/common.py
+++ b/scripts/common.py
@@ -71,6 +71,11 @@ def valid_hashtag(hashtag):
     return True
 
 
+def is_canary(change):
+    # Artificial heartbeat events, which must be discarded.
+    return change.get("meta", {}).get("domain") == "canary"
+
+
 def valid_edit(change):
 
     # Exclude Wikidata for now, just far too much data
diff --git a/scripts/test_common.py b/scripts/test_common.py
new file mode 100644
index 0000000..f8e4851
--- /dev/null
+++ b/scripts/test_common.py
@@ -0,0 +1,18 @@
+import unittest
+
+from common import is_canary
+
+
+class IsCanaryTest(unittest.TestCase):
+    def test_canary_event(self):
+        self.assertTrue(is_canary({"meta": {"domain": "canary"}}))
+
+    def test_normal_event(self):
+        self.assertFalse(is_canary({"meta": {"domain": "en.wikipedia.org"}}))
+
+    def test_missing_meta(self):
+        self.assertFalse(is_canary({}))
+
+
+if __name__ == "__main__":
+    unittest.main()