diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 8d8d42c..bc565e0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -8,7 +8,7 @@ jobs:
     with:
       engine: cruby
       versions: '["truffleruby-head"]'
-      min_version: 2.7
+      min_version: 2.5
 
   build:
     needs: ruby-versions
diff --git a/zlib.gemspec b/zlib.gemspec
index 4a5f8f2..bb67ea1 100644
--- a/zlib.gemspec
+++ b/zlib.gemspec
@@ -27,5 +27,5 @@ Gem::Specification.new do |spec|
   spec.executables   = []
   spec.require_paths = ["lib"]
   spec.extensions    = "ext/zlib/extconf.rb"
-  spec.required_ruby_version = ">= 2.3.0"
+  spec.required_ruby_version = ">= 2.5.0"
 end