diff --git a/Gemfile b/Gemfile
index 30f4ebb4aa..ac492d8ba2 100644
--- a/Gemfile
+++ b/Gemfile
@@ -15,7 +15,7 @@ gem 'rubocop'
 gem 'rubocop-minitest', '0.39.1'
 gem 'rubocop-rake', '0.7.1'
 gem 'simplecov', '0.22.0'
-gem 'test-unit', '3.7.7'
+gem 'test-unit', '3.7.8'
 gem 'timecop', '0.9.11'
 gem 'yard', '0.9.43'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index bed63c97d8..1c8ddb677e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -87,7 +87,7 @@ GEM
     simplecov-html (0.13.2)
     simplecov_json_formatter (0.1.4)
     stringio (3.2.0)
-    test-unit (3.7.7)
+    test-unit (3.7.8)
       power_assert
     timecop (0.9.11)
     tsort (0.2.0)
@@ -114,7 +114,7 @@ DEPENDENCIES
   rubocop-minitest (= 0.39.1)
   rubocop-rake (= 0.7.1)
   simplecov (= 0.22.0)
-  test-unit (= 3.7.7)
+  test-unit (= 3.7.8)
   timecop (= 0.9.11)
   yard (= 0.9.43)