diff --git a/crates/ruma-client-api/CHANGELOG.md b/crates/ruma-client-api/CHANGELOG.md
index b98d3b4b..6abc45bb 100644
--- a/crates/ruma-client-api/CHANGELOG.md
+++ b/crates/ruma-client-api/CHANGELOG.md
@@ -24,6 +24,8 @@ Breaking changes:
 - Use `OwnedCrossSigningOrDeviceSigningKeyId` instead of `OwnedDeviceKeyId` to
   identify signing keys in `BackupAlgorithm::MegolmBackupV1Curve25519AesSha2`'s
   `signatures`.
+- Use `CrossSigningOrDeviceSignatures` for the `signatures` of `BackupAlgorithm`.
+- Use `ServerSignatures` for the `signatures` of `ThirdPartySigned`.
 
 Improvements:
 
diff --git a/crates/ruma-client-api/src/backup.rs b/crates/ruma-client-api/src/backup.rs
index caaad95b..3e4d3f02 100644
--- a/crates/ruma-client-api/src/backup.rs
+++ b/crates/ruma-client-api/src/backup.rs
@@ -20,7 +20,7 @@ use std::collections::BTreeMap;
 use js_int::UInt;
 use ruma_common::{
     serde::{Base64, Raw},
-    OwnedCrossSigningOrDeviceSigningKeyId, OwnedUserId,
+    CrossSigningOrDeviceSignatures,
 };
 use serde::{Deserialize, Serialize};
 
@@ -51,7 +51,7 @@ pub enum BackupAlgorithm {
         public_key: Base64,
 
         /// Signatures of the auth_data as Signed JSON.
-        signatures: BTreeMap<OwnedUserId, BTreeMap<OwnedCrossSigningOrDeviceSigningKeyId, String>>,
+        signatures: CrossSigningOrDeviceSignatures,
     },
 }
 
diff --git a/crates/ruma-client-api/src/membership.rs b/crates/ruma-client-api/src/membership.rs
index 3e0ec168..008b9499 100644
--- a/crates/ruma-client-api/src/membership.rs
+++ b/crates/ruma-client-api/src/membership.rs
@@ -14,9 +14,7 @@ pub mod leave_room;
 pub mod mutual_rooms;
 pub mod unban_user;
 
-use std::collections::BTreeMap;
-
-use ruma_common::{thirdparty::Medium, OwnedServerName, OwnedServerSigningKeyId, OwnedUserId};
+use ruma_common::{thirdparty::Medium, OwnedUserId, ServerSignatures};
 use serde::{Deserialize, Serialize};
 
 /// A signature of an `m.third_party_invite` token to prove that this user owns a third party
@@ -34,7 +32,7 @@ pub struct ThirdPartySigned {
     pub token: String,
 
     /// A signatures object containing a signature of the entire signed object.
-    pub signatures: BTreeMap<OwnedServerName, BTreeMap<OwnedServerSigningKeyId, String>>,
+    pub signatures: ServerSignatures,
 }
 
 impl ThirdPartySigned {
@@ -44,7 +42,7 @@ impl ThirdPartySigned {
         sender: OwnedUserId,
         mxid: OwnedUserId,
         token: String,
-        signatures: BTreeMap<OwnedServerName, BTreeMap<OwnedServerSigningKeyId, String>>,
+        signatures: ServerSignatures,
     ) -> Self {
         Self { sender, mxid, token, signatures }
     }