diff --git a/src/UrlHelper.php b/src/UrlHelper.php
index 625132c..c34d376 100644
--- a/src/UrlHelper.php
+++ b/src/UrlHelper.php
@@ -27,10 +27,14 @@ public static function parseQueryTokenFromUrl(string $url, string $queryKey = 't
         return self::parseTokenFromQueryString($queryString, $queryKey);
     }
 
-    public static function parseTokenFromQueryString(string $queryString, string $queryKey = 'token'): string|array
+    public static function parseTokenFromQueryString(string $queryString, string $queryKey = 'token'): null|string|array
     {
         parse_str($queryString, $output);
 
-        return $output[$queryKey];
+        if (! isset($output[$queryKey])) {
+            return null;
+        }
+
+        return $output[$queryKey] ?? null;
     }
 }
diff --git a/tests/Unit/UrlHelperTest.php b/tests/Unit/UrlHelperTest.php
new file mode 100644
index 0000000..b1a1335
--- /dev/null
+++ b/tests/Unit/UrlHelperTest.php
@@ -0,0 +1,41 @@
+<?php
+
+uses(\Pelmered\LaravelHttpOAuthHelper\Tests\TestCase::class);
+
+use Illuminate\Support\Facades\Http;
+use Pelmered\LaravelHttpOAuthHelper\UrlHelper;
+
+test('UrLHelper parseQueryTokenFromResponse', function (array $params, ?string $result) {
+    $response = Http::post(...$params[0]);
+    $token    = UrlHelper::parseQueryTokenFromResponse($response, $params[1]);
+
+    expect($token)->toEqual($result);
+})->with([
+    'normal' => [[['https://example.com/oauth/token?token=this_is_my_access_token_from_url', []], 'token'], 'this_is_my_access_token_from_url'],
+    'empty'  => [[['https://example.com/oauth/token?token=', []], 'token'], null],
+    'custom' => [[['https://example.com/oauth/token?custom=this_is_my_access_token_from_url', []], 'custom'], 'this_is_my_access_token_from_url'],
+    'wrong'  => [[['https://example.com/oauth/token?token=this_is_my_access_token_from_url', []], 'wrong'], null],
+]);
+
+test('UrLHelper parseQueryTokenFromUrl', function (array $params, ?string $result) {
+    $token = UrlHelper::parseQueryTokenFromUrl(...$params);
+
+    expect($token)->toEqual($result);
+})->with([
+    'normal' => [['https://example.com/oauth/token?token=this_is_my_access_token_from_url'], 'this_is_my_access_token_from_url'],
+    'empty'  => [['https://example.com/oauth/token'], null],
+    'custom' => [['https://example.com/oauth/token?custom=this_is_my_access_token_from_url', 'custom'], 'this_is_my_access_token_from_url'],
+    'wrong'  => [['https://example.com/oauth/token?token=this_is_my_access_token_from_url', 'wrong'], null],
+]);
+
+test('UrLHelper parseTokenFromQueryString', function ($params, $result) {
+
+    $token = UrlHelper::parseTokenFromQueryString(...$params);
+
+    expect($token)->toEqual($result);
+})->with([
+    'normal'               => [['token=this_is_my_access_token_from_url'], 'this_is_my_access_token_from_url'],
+    'invalid query string' => [['something_random'], null],
+    'custom key'           => [['key=this_is_another_token_from_url', 'key'], 'this_is_another_token_from_url'],
+    'wrong key specified'  => [['key=this_is_another_token_from_url', 'other_key'], null],
+]);