diff --git a/Gemfile.lock b/Gemfile.lock
index 1339107..1447264 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -130,6 +130,7 @@ GEM
     multi_xml (0.5.5)
     multipart-post (2.0.0)
     net-ldap (0.11)
+    nio4r (2.5.8)
     nokogiri (1.10.1)
       mini_portile2 (~> 2.4.0)
     nokogumbo (1.4.7)
@@ -145,7 +146,8 @@ GEM
     orm_adapter (0.5.0)
     pg (0.18.4)
     public_suffix (3.0.3)
-    puma (2.16.0)
+    puma (4.3.9)
+      nio4r (~> 2.0)
     rack (1.6.11)
     rack-test (0.6.3)
       rack (>= 1.0)