diff --git a/.gitignore b/.gitignore
index 6ef6a2e3..3cfd3d05 100644
--- a/.gitignore
+++ b/.gitignore
@@ -18,6 +18,13 @@ Thumbs.db
 # Local dev overrides
 .env
 
+# The static-analysis database `tools/zq.py` reads by default. A build artefact
+# of several hundred MB (`sylph-xexdb dis ... --db sylpheed.db`), and zq.py
+# now tells people to put it exactly here -- so it must never be committable.
+# One `git add -A` would otherwise put it in public history for good.
+/sylpheed.db
+/sylpheed.db.wal
+
 # Trunk build output
 dist/
 __pycache__/