diff --git a/src/crypto/EncryptionSetup.ts b/src/crypto/EncryptionSetup.ts
index cb208b9cc..442149b90 100644
--- a/src/crypto/EncryptionSetup.ts
+++ b/src/crypto/EncryptionSetup.ts
@@ -59,7 +59,7 @@ export class EncryptionSetupBuilder {
      * @param {Object.<String, MatrixEvent>} accountData pre-existing account data, will only be read, not written.
      * @param {CryptoCallbacks} delegateCryptoCallbacks crypto callbacks to delegate to if the key isn't in cache yet
      */
-    constructor(accountData: Record<string, MatrixEvent>, delegateCryptoCallbacks: ICryptoCallbacks) {
+    constructor(accountData: Record<string, MatrixEvent>, delegateCryptoCallbacks?: ICryptoCallbacks) {
         this.accountDataClientAdapter = new AccountDataClientAdapter(accountData);
         this.crossSigningCallbacks = new CrossSigningCallbacks();
         this.ssssCryptoCallbacks = new SSSSCryptoCallbacks(delegateCryptoCallbacks);