diff --git a/Gemfile.lock b/Gemfile.lock
index 2e02715..a2b8d0b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -6,12 +6,12 @@ GEM
       builder (>= 2.1.2)
     log4r (1.1.10)
     power_assert (2.0.3)
-    psych (5.1.0)
+    psych (5.1.2)
       stringio
     rake (13.0.6)
-    rdoc (6.5.0)
+    rdoc (6.5.1.1)
       psych (>= 4.0.0)
-    stringio (3.0.8)
+    stringio (3.1.0)
     test-unit (3.6.1)
       power_assert
     tokyocabinet (1.32.0)