diff --git a/wildduck_exporter.py b/wildduck_exporter.py
index c8a3a3d..f244d6d 100755
--- a/wildduck_exporter.py
+++ b/wildduck_exporter.py
@@ -58,7 +58,7 @@ async def fetch():
 
     # Merge application specific passwords last used timestamps
     async for a in app.ctx.db.asps.find({"user": {"$in": list(last_login.keys())}}):
-        if a["used"] > last_login[a["user"]]:
+        if a["used"] and a["used"] > last_login[a["user"]]:
             last_login[a["user"]] = a["used"]
 
     for user, dt in last_login.items():