diff --git a/Gemfile.lock b/Gemfile.lock
index 3a225c1..2d7e7ac 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -12,7 +12,9 @@ GEM
     i18n (1.6.0)
       concurrent-ruby (~> 1.0)
     minitest (5.11.3)
-    puma (3.12.1)
+    nio4r (2.5.8)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rspec (3.1.0)
       rspec-core (~> 3.1.0)