diff --git a/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb b/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
index 32cd05b0c1..b137ce6d32 100644
--- a/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
+++ b/Library/Homebrew/test/dev-cmd/determine-test-runners_spec.rb
@@ -31,7 +31,8 @@ RSpec.describe Homebrew::DevCmd::DetermineTestRunners do
     out = []
     MacOSVersion::SYMBOLS.each_value do |v|
       macos_version = MacOSVersion.new(v)
-      next if macos_version.unsupported_release?
+      next if macos_version < :monterey
+      next if macos_version > :sonoma
 
       out << "#{v}-x86_64"
       out << "#{v}-arm64"
diff --git a/Library/Homebrew/test/github_runner_matrix_spec.rb b/Library/Homebrew/test/github_runner_matrix_spec.rb
index 99f457e01e..ab4850ff71 100644
--- a/Library/Homebrew/test/github_runner_matrix_spec.rb
+++ b/Library/Homebrew/test/github_runner_matrix_spec.rb
@@ -11,8 +11,9 @@ RSpec.describe GitHubRunnerMatrix do
     allow(ENV).to receive(:fetch).with("GITHUB_RUN_ID").and_return("12345")
   end
 
+  # FIXME: Avoid changing this every time we change Homebrew/core CI runner macOS versions.
   let(:newest_supported_macos) do
-    MacOSVersion::SYMBOLS.find { |_, v| !MacOSVersion.new(v).prerelease? }
+    MacOSVersion::SYMBOLS.find { |k, _| k == :sonoma }
   end
 
   let(:testball) { TestRunnerFormula.new(Testball.new) }