diff --git a/tests/lib/TestCase.php b/tests/lib/TestCase.php
index 551c1024e0bef..5efa5249bc53e 100644
--- a/tests/lib/TestCase.php
+++ b/tests/lib/TestCase.php
@@ -91,7 +91,9 @@ public function restoreService(string $name): bool {
 					return $oldService;
 				});
 			} else {
-				unset($container[$oldService]);
+				// The service was not registered before the test override.
+				// Remove the test registration so the container returns to its prior state.
+				unset($container[$name]);
 			}