diff --git a/Gemfile.lock b/Gemfile.lock
index bb5d381..52c4bb1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -14,6 +14,8 @@ GEM
     jaro_winkler (1.5.2-java)
     method_source (0.9.2)
     mustermann (1.0.3)
+    nio4r (2.5.8)
+    nio4r (2.5.8-java)
     parallel (1.17.0)
     parser (2.6.3.0)
       ast (~> 2.4.0)
@@ -24,8 +26,10 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
       spoon (~> 0.0)
-    puma (3.12.6)
-    puma (3.12.6-java)
+    puma (4.3.12)
+      nio4r (~> 2.0)
+    puma (4.3.12-java)
+      nio4r (~> 2.0)
     rack (2.2.3)
     rack-protection (2.0.5)
       rack