diff --git a/01-docker-images/demo/Gemfile.lock b/01-docker-images/demo/Gemfile.lock
index 40de027..f9ce852 100644
--- a/01-docker-images/demo/Gemfile.lock
+++ b/01-docker-images/demo/Gemfile.lock
@@ -186,7 +186,7 @@ GEM
       railties (>= 5.0)
     websocket-driver (0.7.0)
       websocket-extensions (>= 0.1.0)
-    websocket-extensions (0.1.3)
+    websocket-extensions (0.1.5)
     xpath (3.2.0)
       nokogiri (~> 1.8)