diff --git a/src/Plugins/Tia/CiDefaultBranch.php b/src/Plugins/Tia/CiDefaultBranch.php
index 3db30f5f..682a506e 100644
--- a/src/Plugins/Tia/CiDefaultBranch.php
+++ b/src/Plugins/Tia/CiDefaultBranch.php
@@ -4,56 +4,31 @@ declare(strict_types=1);
 
 namespace Pest\Plugins\Tia;
 
+use Pest\Plugins\Tia\Contracts\Ci;
+
 /**
  * @internal
  */
 final class CiDefaultBranch
 {
+    /**
+     * @var array<int, class-string<Ci>>
+     */
+    private const array CIS = [
+        Cis\GitLab::class,
+        Cis\GitHub::class,
+    ];
+
     public static function detect(): ?string
     {
-        return self::fromGitLab() ?? self::fromGitHubEvent();
-    }
+        foreach (self::CIS as $class) {
+            $branch = (new $class)->defaultBranch();
 
-    private static function fromGitLab(): ?string
-    {
-        return self::environment('CI_DEFAULT_BRANCH');
-    }
-
-    private static function fromGitHubEvent(): ?string
-    {
-        $path = self::environment('GITHUB_EVENT_PATH');
-
-        if ($path === null || ! is_file($path) || ! is_readable($path)) {
-            return null;
+            if ($branch !== null) {
+                return $branch;
+            }
         }
 
-        $contents = @file_get_contents($path);
-
-        if ($contents === false) {
-            return null;
-        }
-
-        $payload = json_decode($contents, true);
-
-        if (! is_array($payload) || ! is_array($payload['repository'] ?? null)) {
-            return null;
-        }
-
-        $branch = $payload['repository']['default_branch'] ?? null;
-
-        return is_string($branch) && $branch !== '' ? $branch : null;
-    }
-
-    private static function environment(string $name): ?string
-    {
-        $value = getenv($name);
-
-        if (! is_string($value)) {
-            return null;
-        }
-
-        $value = trim($value);
-
-        return $value === '' ? null : $value;
+        return null;
     }
 }
diff --git a/src/Plugins/Tia/Cis/Concerns/ReadsEnvironment.php b/src/Plugins/Tia/Cis/Concerns/ReadsEnvironment.php
new file mode 100644
index 00000000..60ea4053
--- /dev/null
+++ b/src/Plugins/Tia/Cis/Concerns/ReadsEnvironment.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\Cis\Concerns;
+
+/**
+ * @internal
+ */
+trait ReadsEnvironment
+{
+    private function environment(string $name): ?string
+    {
+        $value = getenv($name);
+
+        if (! is_string($value)) {
+            return null;
+        }
+
+        $value = trim($value);
+
+        return $value === '' ? null : $value;
+    }
+}
diff --git a/src/Plugins/Tia/Cis/GitHub.php b/src/Plugins/Tia/Cis/GitHub.php
new file mode 100644
index 00000000..b0d5d787
--- /dev/null
+++ b/src/Plugins/Tia/Cis/GitHub.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\Cis;
+
+use Pest\Plugins\Tia\Cis\Concerns\ReadsEnvironment;
+use Pest\Plugins\Tia\Contracts\Ci;
+
+/**
+ * @internal
+ */
+final readonly class GitHub implements Ci
+{
+    use ReadsEnvironment;
+
+    public function defaultBranch(): ?string
+    {
+        $path = $this->environment('GITHUB_EVENT_PATH');
+
+        if ($path === null || ! is_file($path) || ! is_readable($path)) {
+            return null;
+        }
+
+        $contents = @file_get_contents($path);
+
+        if ($contents === false) {
+            return null;
+        }
+
+        $payload = json_decode($contents, true);
+
+        if (! is_array($payload) || ! is_array($payload['repository'] ?? null)) {
+            return null;
+        }
+
+        $branch = $payload['repository']['default_branch'] ?? null;
+
+        return is_string($branch) && $branch !== '' ? $branch : null;
+    }
+}
diff --git a/src/Plugins/Tia/Cis/GitLab.php b/src/Plugins/Tia/Cis/GitLab.php
new file mode 100644
index 00000000..06db0f1b
--- /dev/null
+++ b/src/Plugins/Tia/Cis/GitLab.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\Cis;
+
+use Pest\Plugins\Tia\Cis\Concerns\ReadsEnvironment;
+use Pest\Plugins\Tia\Contracts\Ci;
+
+/**
+ * @internal
+ */
+final readonly class GitLab implements Ci
+{
+    use ReadsEnvironment;
+
+    public function defaultBranch(): ?string
+    {
+        return $this->environment('CI_DEFAULT_BRANCH');
+    }
+}
diff --git a/src/Plugins/Tia/Contracts/Ci.php b/src/Plugins/Tia/Contracts/Ci.php
new file mode 100644
index 00000000..53fc2a6f
--- /dev/null
+++ b/src/Plugins/Tia/Contracts/Ci.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia\Contracts;
+
+/**
+ * @internal
+ */
+interface Ci
+{
+    /**
+     * The default branch advertised by this CI, or `null` when the run
+     * does not happen on it — or when it exposes no such information.
+     */
+    public function defaultBranch(): ?string;
+}