diff --git a/system/HTTP/RequestTrait.php b/system/HTTP/RequestTrait.php
index 43a4f23a0e87..a47d4c7a6980 100644
--- a/system/HTTP/RequestTrait.php
+++ b/system/HTTP/RequestTrait.php
@@ -290,7 +290,7 @@ public function fetchGlobal(string $name, $index = null, ?int $filter = null, $f
         }
 
         // Does the index contain array notation?
-        if (($count = preg_match_all('/(?:^[^\[]+)|\[[^]]*\]/', $index, $matches)) > 1) {
+        if (is_string($index) && ($count = preg_match_all('/(?:^[^\[]+)|\[[^]]*\]/', $index, $matches)) > 1) {
             $value = $this->globals[$name];
 
             for ($i = 0; $i < $count; $i++) {
diff --git a/tests/system/Test/FeatureTestTraitTest.php b/tests/system/Test/FeatureTestTraitTest.php
index be3d590bd15a..cd1c845342f1 100644
--- a/tests/system/Test/FeatureTestTraitTest.php
+++ b/tests/system/Test/FeatureTestTraitTest.php
@@ -557,7 +557,7 @@ public function testCallPutWithJsonRequestAndREQUEST(): void
         $this->assertStringContainsString('[]', $response->getBody());
     }
 
-    public function testCallWithJsonRequest(): void
+    public function testCallWithAssociativeJsonRequest(): void
     {
         $this->withRoutes([
             [
@@ -581,6 +581,26 @@ public function testCallWithJsonRequest(): void
         $response->assertJSONExact($data);
     }
 
+    public function testCallWithListJsonRequest(): void
+    {
+        $this->withRoutes([
+            [
+                'POST',
+                'home',
+                '\Tests\Support\Controllers\Popcorn::echoJson',
+            ],
+        ]);
+        $data = [
+            ['one' => 1, 'two' => 2],
+            ['one' => 2, 'two' => 2],
+        ];
+        $response = $this->withBodyFormat('json')
+            ->call(Method::POST, 'home', $data);
+
+        $response->assertOK();
+        $response->assertJSONExact($data);
+    }
+
     public function testSetupRequestBodyWithParams(): void
     {
         $request = $this->setupRequest('post', 'home');