diff --git a/src/service/rooms/timeline/mod.rs b/src/service/rooms/timeline/mod.rs
index 493938a9..11f1d701 100644
--- a/src/service/rooms/timeline/mod.rs
+++ b/src/service/rooms/timeline/mod.rs
@@ -814,8 +814,10 @@ impl Service {
         }
 
         // Hash and sign
-        let mut pdu_json =
-            utils::to_canonical_object(&pdu).expect("event is valid, we just created it");
+        let mut pdu_json = utils::to_canonical_object(&pdu).map_err(|e| {
+            error!("Failed to convert PDU {:?} to canonical JSON: {}", &pdu, e);
+            Error::bad_database("Failed to convert PDU to canonical JSON.")
+        })?;
 
         pdu_json.remove("event_id");