diff --git a/src/wallet/MoneroWallet.cpp b/src/wallet/MoneroWallet.cpp
index e2dc404..62837ea 100644
--- a/src/wallet/MoneroWallet.cpp
+++ b/src/wallet/MoneroWallet.cpp
@@ -128,6 +128,11 @@ uint64_t MoneroWallet::getRestoreHeight() const {
   return wallet2->get_refresh_from_block_height();
 }
 
+void MoneroWallet::setListener(MoneroWalletListener* listener) {
+  cout << "setListener()" << endl;
+  throw runtime_error("Not implemented");
+}
+
 MoneroSyncResult MoneroWallet::sync() {
   cout << "sync()" << endl;
   throw runtime_error("Not implemented");
diff --git a/src/wallet/MoneroWallet.h b/src/wallet/MoneroWallet.h
index ecdf625..25271e1 100644
--- a/src/wallet/MoneroWallet.h
+++ b/src/wallet/MoneroWallet.h
@@ -26,7 +26,8 @@ namespace monero {
    * Models a result of syncing a wallet.
    */
   struct MoneroBlockHeader {
-    // TODO
+    uint64_t height;
+    MoneroBlockHeader() {}
   };
 
   /**
@@ -78,7 +79,7 @@ namespace monero {
      * @param percentDone is the sync progress as a percentage
      * @param message is a human-readable description of the current progress
      */
-    virtual void onSyncProgress(uint64_t startHeight, uint64_t numBlocksDone, uint64_t numBlocksTotal, double percentDone, string message);
+    virtual void onSyncProgress(uint64_t startHeight, uint64_t numBlocksDone, uint64_t numBlocksTotal, double percentDone, string message) {}
   };
 
   /**
@@ -91,7 +92,7 @@ namespace monero {
      *
      * @param block is the newly processed block
      */
-    virtual void onNewBlock(MoneroBlock& block);
+    virtual void onNewBlock(MoneroBlock& block) {};
   };
 
   // ---------------------------- WALLET INTERFACE ----------------------------
@@ -228,6 +229,8 @@ namespace monero {
 
    uint64_t getRestoreHeight() const;
 
+   void setListener(MoneroWalletListener* listener);
+
    MoneroSyncResult sync();
 
    MoneroSyncResult sync(MoneroSyncListener& listener);