diff --git a/Gemfile b/Gemfile
index eb755b90d04..20cc48a567e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ git_source(:github) { |repo| "https://github.com/#{repo}.git" }
 
 gemspec
 
-gem "minitest", ">= 5.15.0"
+gem "minitest", ">= 5.15.0", "< 5.16.0"
 
 # We need a newish Rake since Active Job sets its test tasks' descriptions.
 gem "rake", ">= 11.1"
diff --git a/Gemfile.lock b/Gemfile.lock
index eedd1de8a31..91a71fb8870 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -586,7 +586,7 @@ DEPENDENCIES
   kindlerb (~> 1.2.0)
   libxml-ruby
   listen (~> 3.3)
-  minitest (>= 5.15.0)
+  minitest (>= 5.15.0, < 5.16.0)
   minitest-bisect
   minitest-ci
   minitest-retry