diff --git a/Gemfile b/Gemfile
index f5a62b3..de631a1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,7 @@ gemspec
 gem "webrick", "~> 1.7"
 gem "minitest", "~> 5.7"
 gem "rdoc", "< 7", ">= 4.0"
+gem "logger", "~> 1.7"
 gem "builder", "~> 3.2"
 gem "rubygems-generate_index"
 gem "rake"