diff --git a/docs-layout/docs-book/Gemfile.lock b/docs-layout/docs-book/Gemfile.lock
index 5ba9202..d01dbe0 100644
--- a/docs-layout/docs-book/Gemfile.lock
+++ b/docs-layout/docs-book/Gemfile.lock
@@ -145,6 +145,7 @@ GEM
     minitest (5.9.0)
     multi_json (1.12.1)
     multipart-post (2.0.0)
+    nio4r (2.5.9)
     nokogiri (1.6.7.2)
       mini_portile2 (~> 2.0.0.rc2)
     padrino-helpers (0.12.8)
@@ -153,7 +154,8 @@ GEM
       tilt (~> 1.4.1)
     padrino-support (0.12.8)
       activesupport (>= 3.1)
-    puma (3.6.0)
+    puma (6.3.1)
+      nio4r (~> 2.0)
     rack (1.6.4)
     rack-livereload (0.3.16)
       rack