diff --git a/src/api/client_server/membership.rs b/src/api/client_server/membership.rs
index 5c0169d2..3f3d25d5 100644
--- a/src/api/client_server/membership.rs
+++ b/src/api/client_server/membership.rs
@@ -627,7 +627,7 @@ async fn join_room_by_id_helper(
         let event_id = format!(
             "${}",
             ruma::signatures::reference_hash(&join_event_stub, &room_version_id)
-                .expect("ruma can calculate reference hashes")
+                .expect("Event format validated when event was hashed")
         );
         let event_id = <&EventId>::try_from(event_id.as_str())
             .expect("ruma's reference hashes are valid event ids");
@@ -1145,7 +1145,7 @@ async fn validate_and_add_event_id(
     let event_id = EventId::parse(format!(
         "${}",
         ruma::signatures::reference_hash(&value, room_version)
-            .expect("ruma can calculate reference hashes")
+            .map_err(|_| Error::BadRequest(ErrorKind::BadJson, "Invalid PDU format"))?
     ))
     .expect("ruma's reference hashes are valid event ids");
 
@@ -1614,7 +1614,7 @@ async fn remote_leave_room(user_id: &UserId, room_id: &RoomId) -> Result<()> {
     let event_id = EventId::parse(format!(
         "${}",
         ruma::signatures::reference_hash(&leave_event_stub, &room_version_id)
-            .expect("ruma can calculate reference hashes")
+            .expect("Event format validated when event was hashed")
     ))
     .expect("ruma's reference hashes are valid event ids");
 
diff --git a/src/api/server_server.rs b/src/api/server_server.rs
index a2051251..9f5ed24c 100644
--- a/src/api/server_server.rs
+++ b/src/api/server_server.rs
@@ -1815,7 +1815,7 @@ pub async fn create_invite_route(
     let event_id = EventId::parse(format!(
         "${}",
         ruma::signatures::reference_hash(&signed_event, &body.room_version)
-            .expect("ruma can calculate reference hashes")
+            .expect("Event format validated when event was hashed")
     ))
     .expect("ruma's reference hashes are valid event ids");
 
diff --git a/src/service/pdu.rs b/src/service/pdu.rs
index dab7b6e0..7934909b 100644
--- a/src/service/pdu.rs
+++ b/src/service/pdu.rs
@@ -1,5 +1,6 @@
 use crate::Error;
 use ruma::{
+    api::client::error::ErrorKind,
     canonical_json::redact_content_in_place,
     events::{
         room::{member::RoomMemberEventContent, redaction::RoomRedactionEventContent},
@@ -443,7 +444,7 @@ pub(crate) fn gen_event_id_canonical_json(
         "${}",
         // Anything higher than version3 behaves the same
         ruma::signatures::reference_hash(&value, room_version_id)
-            .expect("ruma can calculate reference hashes")
+            .map_err(|_| Error::BadRequest(ErrorKind::BadJson, "Invalid PDU format"))?
     )
     .try_into()
     .expect("ruma's reference hashes are valid event ids");
diff --git a/src/service/rooms/event_handler/mod.rs b/src/service/rooms/event_handler/mod.rs
index 002b8d77..0dd405c7 100644
--- a/src/service/rooms/event_handler/mod.rs
+++ b/src/service/rooms/event_handler/mod.rs
@@ -1477,7 +1477,7 @@ impl Service {
         let event_id = format!(
             "${}",
             ruma::signatures::reference_hash(&value, room_version)
-                .expect("ruma can calculate reference hashes")
+                .map_err(|_| Error::BadRequest(ErrorKind::BadJson, "Invalid PDU format"))?
         );
         let event_id = <&EventId>::try_from(event_id.as_str())
             .expect("ruma's reference hashes are valid event ids");
diff --git a/src/service/rooms/timeline/mod.rs b/src/service/rooms/timeline/mod.rs
index 6603ea65..9f0e2905 100644
--- a/src/service/rooms/timeline/mod.rs
+++ b/src/service/rooms/timeline/mod.rs
@@ -815,7 +815,7 @@ impl Service {
         pdu.event_id = EventId::parse_arc(format!(
             "${}",
             ruma::signatures::reference_hash(&pdu_json, &room_version_id)
-                .expect("ruma can calculate reference hashes")
+                .expect("Event format validated when event was hashed")
         ))
         .expect("ruma's reference hashes are valid event ids");