diff --git a/api/notifications/controller.go b/api/notifications/controller.go
index 353ea84..1ce6919 100644
--- a/api/notifications/controller.go
+++ b/api/notifications/controller.go
@@ -136,10 +136,11 @@ func (c *Controller) Subscribe(_ context.Context, topic string, handler layer.Ms
 	ch := make(chan *nats.Msg, 1)
 
 	c.mu.RLock()
-	if _, ok := c.handlers[topic]; ok {
+	_, ok := c.handlers[topic]
+	c.mu.RUnlock()
+	if ok {
 		return fmt.Errorf("already subscribed to topic '%s'", topic)
 	}
-	c.mu.RUnlock()
 
 	if _, err := c.jsClient.AddStream(&nats.StreamConfig{Name: topic}); err != nil {
 		return fmt.Errorf("add stream: %w", err)