diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5bcd688..ac51672 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -7,7 +7,7 @@ jobs:
     name: build (${{ matrix.ruby }} / ${{ matrix.os }})
     strategy:
       matrix:
-        ruby: [ '3.0', head ]
+        ruby: [ 2.7, '3.0', head ]
         os: [ ubuntu-latest, macos-latest, windows-latest ]
         exclude:
         - { os: windows-latest , ruby: head }
diff --git a/pathname.gemspec b/pathname.gemspec
index 5aaa8f8..c9c0b84 100644
--- a/pathname.gemspec
+++ b/pathname.gemspec
@@ -7,7 +7,7 @@ Gem::Specification.new do |spec|
   spec.summary       = %q{Representation of the name of a file or directory on the filesystem}
   spec.description   = %q{Representation of the name of a file or directory on the filesystem}
   spec.homepage      = "https://github.com/ruby/pathname"
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.7.0")
   spec.licenses      = ["Ruby", "BSD-2-Clause"]
 
   spec.metadata["homepage_uri"] = spec.homepage
diff --git a/test/lib/core_assertions.rb b/test/lib/core_assertions.rb
index 4471525..720883a 100644
--- a/test/lib/core_assertions.rb
+++ b/test/lib/core_assertions.rb
@@ -695,7 +695,7 @@ def assert_join_threads(threads, message = nil)
           msg = "exceptions on #{errs.length} threads:\n" +
             errs.map {|t, err|
             "#{t.inspect}:\n" +
-              RUBY_VERSION >= "2.5.0" ? err.full_message(highlight: false, order: :top) : err.message
+              err.full_message(highlight: false, order: :top)
           }.join("\n---\n")
           if message
             msg = "#{message}\n#{msg}"