diff --git a/crates/matrix-sdk-crypto/src/olm/account.rs b/crates/matrix-sdk-crypto/src/olm/account.rs
index 8eb52770d..f332f018d 100644
--- a/crates/matrix-sdk-crypto/src/olm/account.rs
+++ b/crates/matrix-sdk-crypto/src/olm/account.rs
@@ -746,17 +746,16 @@ impl ReadOnlyAccount {
 
     pub(crate) fn unsigned_device_keys(&self) -> DeviceKeys {
         let identity_keys = self.identity_keys();
-
-        let mut keys = BTreeMap::new();
-
-        keys.insert(
-            DeviceKeyId::from_parts(DeviceKeyAlgorithm::Curve25519, &self.device_id),
-            identity_keys.curve25519().to_owned(),
-        );
-        keys.insert(
-            DeviceKeyId::from_parts(DeviceKeyAlgorithm::Ed25519, &self.device_id),
-            identity_keys.ed25519().to_owned(),
-        );
+        let keys = BTreeMap::from([
+            (
+                DeviceKeyId::from_parts(DeviceKeyAlgorithm::Curve25519, &self.device_id),
+                identity_keys.curve25519().to_owned(),
+            ),
+            (
+                DeviceKeyId::from_parts(DeviceKeyAlgorithm::Ed25519, &self.device_id),
+                identity_keys.ed25519().to_owned(),
+            ),
+        ]);
 
         DeviceKeys::new(
             (*self.user_id).clone(),
diff --git a/crates/matrix-sdk-crypto/src/olm/signing/pk_signing.rs b/crates/matrix-sdk-crypto/src/olm/signing/pk_signing.rs
index 964da3554..750340497 100644
--- a/crates/matrix-sdk-crypto/src/olm/signing/pk_signing.rs
+++ b/crates/matrix-sdk-crypto/src/olm/signing/pk_signing.rs
@@ -397,13 +397,11 @@ impl Signing {
     }
 
     pub fn cross_signing_key(&self, user_id: UserId, usage: KeyUsage) -> CrossSigningKey {
-        let mut keys = BTreeMap::new();
-
-        keys.insert(
+        let keys = BTreeMap::from([(
             DeviceKeyId::from_parts(DeviceKeyAlgorithm::Ed25519, self.public_key().as_str().into())
                 .to_string(),
             self.public_key().to_string(),
-        );
+        )]);
 
         CrossSigningKey::new(user_id, vec![usage], keys, BTreeMap::new())
     }