diff --git a/tests/Exception/MissingSecretKeyTest.php b/tests/Exception/MissingSecretKeyTest.php
new file mode 100644
index 0000000..f968876
--- /dev/null
+++ b/tests/Exception/MissingSecretKeyTest.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SnapAuth\Exception;
+
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Small;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+#[CoversClass(MissingSecretKey::class)]
+#[Small]
+class MissingSecretKeyTest extends TestCase
+{
+    public function testConstruct(): void
+    {
+        $e = new MissingSecretKey();
+        self::assertStringContainsString('SNAPAUTH_SECRET_KEY', $e->getMessage());
+    }
+}