diff --git a/Gemfile.lock b/Gemfile.lock
index 5fc1c8c..dc01383 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -21,7 +21,8 @@ GEM
     rainbow (3.1.1)
     rake (13.0.6)
     regexp_parser (2.3.0)
-    rexml (3.2.5)
+    rexml (3.3.6)
+      strscan
     rspec (3.11.0)
       rspec-core (~> 3.11.0)
       rspec-expectations (~> 3.11.0)
@@ -52,6 +53,7 @@ GEM
       rubocop (~> 1.19)
     ruby-progressbar (1.11.0)
     ruby2_keywords (0.0.5)
+    strscan (3.1.0)
     unicode-display_width (1.8.0)
     webrick (1.7.0)
     yard (0.9.27)