diff --git a/tests/mock/sysrepo_subscription.cpp b/tests/mock/sysrepo_subscription.cpp
index 801ec1c..7cd5cf3 100644
--- a/tests/mock/sysrepo_subscription.cpp
+++ b/tests/mock/sysrepo_subscription.cpp
@@ -28,9 +28,11 @@
             return SR_ERR_OK;
 
         while (auto change = sess->get_change_next(it)) {
-            m_recorder->write(change->new_val()->xpath(),
-                              change->old_val() ? change->old_val()->val_to_string() : "",
-                              change->new_val()->val_to_string());
+            auto xpath = (change->new_val() ? change->new_val() : change->old_val())->xpath();
+
+            auto oldValue = change->old_val() ? std::optional{change->old_val()->val_to_string()} : std::nullopt;
+            auto newValue = change->new_val() ? std::optional{change->new_val()->val_to_string()} : std::nullopt;
+            m_recorder->write(xpath, oldValue, newValue);
         }
 
         return SR_ERR_OK;