diff --git a/cmd/server/tests/ownership_and_admin_test.go b/cmd/server/tests/ownership_and_admin_test.go
index accdda06..427f3759 100644
--- a/cmd/server/tests/ownership_and_admin_test.go
+++ b/cmd/server/tests/ownership_and_admin_test.go
@@ -183,8 +183,10 @@ func (s *OwnershipAndAdminTestSuite) TestHighlightDelete_CrossUserNoOp() {
 // create accounts even with self-service registration disabled, regular
 // users cannot, and duplicates conflict.
 func (s *OwnershipAndAdminTestSuite) TestAdminCreateUser() {
-	suffix := fmt.Sprintf("%d", s.setup.DBPool.Config().MaxConns) // stable-ish uniquifier
-	unique := fmt.Sprintf("admincreated%s", suffix)
+	// Real unique suffix: MaxConns is forced to 1 by the harness, so the old
+	// "stable-ish" uniquifier produced the same user every run and only
+	// survived on the setup-time cleanup sweep of the NEXT run.
+	unique := fmt.Sprintf("admincreated-%s", uuid.New().String()[:8])
 
 	// Regular user token → 403 (AdminMiddleware).
 	payload, _ := json.Marshal(map[string]interface{}{
diff --git a/cmd/server/tests/test_helpers_test.go b/cmd/server/tests/test_helpers_test.go
index dd8e120c..ca84928a 100644
--- a/cmd/server/tests/test_helpers_test.go
+++ b/cmd/server/tests/test_helpers_test.go
@@ -503,6 +503,10 @@ func setupTestServer(t *testing.T) *TestServerSetup {
 	conflictHandler := handlers.NewConflictHandler(queries, connManager, progressService)
 	analyticsHandler := handlers.NewAnalyticsHandler(queries)
 	queueHandler := handlers.NewQueueHandler(queries, queueProcessor)
+	// main.go:112 wires the registry into the auth handler too — without it
+	// defaultTimezone() short-circuits to UTC and every new user (Register +
+	// AdminCreateUser) ignores the system default_timezone setting in tests.
+	authHandler.SetSettings(settingsRegistry)
 	systemSettingsHandler := handlers.NewSystemSettingsHandler(queries)
 	systemSettingsHandler.SetSettings(settingsRegistry)
 	processingIssuesHandler := handlers.NewProcessingIssuesHandler(queries)