diff --git a/Gemfile.lock b/Gemfile.lock
index 874d2bb..52c5a0b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -8,10 +8,10 @@ GEM
   remote: https://rubygems.org/
   specs:
     diff-lcs (1.5.0)
-    psych (4.0.3)
+    psych (5.1.2)
       stringio
     rake (12.3.3)
-    rdoc (6.4.0)
+    rdoc (6.4.1.1)
       psych (>= 4.0.0)
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
@@ -26,7 +26,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.11.0)
     rspec-support (3.11.0)
-    stringio (3.0.1)
+    stringio (3.1.0)
 
 PLATFORMS
   ruby