diff --git a/owlbot-postprocessor/Gemfile b/owlbot-postprocessor/Gemfile
index 5ead025..b0bce7d 100644
--- a/owlbot-postprocessor/Gemfile
+++ b/owlbot-postprocessor/Gemfile
@@ -15,7 +15,7 @@
 source "https://rubygems.org"
 
 gem "google-style", "~> 1.31.0"
-gem "minitest", "~> 5.16"
+gem "minitest", ">= 5.16", "< 7"
 gem "minitest-focus", "~> 1.3"
 gem "minitest-rg", "~> 5.2"
 gem "toys-core", "~> 0.15"