diff --git a/matrix_sdk_crypto/src/machine.rs b/matrix_sdk_crypto/src/machine.rs
index 6bbbce33..5d05dd4a 100644
--- a/matrix_sdk_crypto/src/machine.rs
+++ b/matrix_sdk_crypto/src/machine.rs
@@ -164,7 +164,7 @@ impl OlmMachine {
     /// * `device_id` - The unique id of the device that owns this machine.
     pub async fn new_with_default_store<P: AsRef<Path>>(
         user_id: &UserId,
-        device_id: &str,
+        device_id: &DeviceId,
         path: P,
         passphrase: &str,
     ) -> StoreResult<Self> {
diff --git a/matrix_sdk_crypto/src/memory_stores.rs b/matrix_sdk_crypto/src/memory_stores.rs
index 7cf6351c..72d91395 100644
--- a/matrix_sdk_crypto/src/memory_stores.rs
+++ b/matrix_sdk_crypto/src/memory_stores.rs
@@ -140,7 +140,7 @@ pub struct UserDevices {
 
 impl UserDevices {
     /// Get the specific device with the given device id.
-    pub fn get(&self, device_id: &str) -> Option<Device> {
+    pub fn get(&self, device_id: &DeviceId) -> Option<Device> {
         self.entries.get(device_id).cloned()
     }
 
@@ -180,7 +180,7 @@ impl DeviceStore {
     }
 
     /// Get the device with the given device_id and belonging to the given user.
-    pub fn get(&self, user_id: &UserId, device_id: &str) -> Option<Device> {
+    pub fn get(&self, user_id: &UserId, device_id: &DeviceId) -> Option<Device> {
         self.entries
             .get(user_id)
             .and_then(|m| m.get(device_id).map(|d| d.value().clone()))
@@ -189,7 +189,7 @@ impl DeviceStore {
     /// Remove the device with the given device_id and belonging to the given user.
     ///
     /// Returns the device if it was removed, None if it wasn't in the store.
-    pub fn remove(&self, user_id: &UserId, device_id: &str) -> Option<Device> {
+    pub fn remove(&self, user_id: &UserId, device_id: &DeviceId) -> Option<Device> {
         self.entries
             .get(user_id)
             .and_then(|m| m.remove(device_id))
diff --git a/matrix_sdk_crypto/src/store/sqlite.rs b/matrix_sdk_crypto/src/store/sqlite.rs
index 44feb951..5d69e466 100644
--- a/matrix_sdk_crypto/src/store/sqlite.rs
+++ b/matrix_sdk_crypto/src/store/sqlite.rs
@@ -66,7 +66,7 @@ impl SqliteStore {
     /// * `path` - The path where the database file should reside in.
     pub async fn open<P: AsRef<Path>>(
         user_id: &UserId,
-        device_id: &str,
+        device_id: &DeviceId,
         path: P,
     ) -> Result<SqliteStore> {
         SqliteStore::open_helper(user_id, device_id, path, None).await
@@ -88,7 +88,7 @@ impl SqliteStore {
     /// the encryption keys.
     pub async fn open_with_passphrase<P: AsRef<Path>>(
         user_id: &UserId,
-        device_id: &str,
+        device_id: &DeviceId,
         path: P,
         passphrase: &str,
     ) -> Result<SqliteStore> {
@@ -109,7 +109,7 @@ impl SqliteStore {
 
     async fn open_helper<P: AsRef<Path>>(
         user_id: &UserId,
-        device_id: &str,
+        device_id: &DeviceId,
         path: P,
         passphrase: Option<Zeroizing<String>>,
     ) -> Result<SqliteStore> {
@@ -804,7 +804,7 @@ mod test {
     use super::{Account, CryptoStore, InboundGroupSession, RoomId, Session, SqliteStore, TryFrom};
 
     static USER_ID: &str = "@example:localhost";
-    static DEVICE_ID: &str = "DEVICEID";
+    static DEVICE_ID: &DeviceId = "DEVICEID";
 
     async fn get_store(passphrase: Option<&str>) -> (SqliteStore, tempfile::TempDir) {
         let tmpdir = tempdir().unwrap();