diff --git a/src/ViewTrait.php b/src/ViewTrait.php
index 8a92e98d9..944a608db 100644
--- a/src/ViewTrait.php
+++ b/src/ViewTrait.php
@@ -88,6 +88,16 @@ public function withBasePath(string|null $basePath): static
     public function withRenderers(array $renderers): static
     {
         foreach ($renderers as $extension => $renderer) {
+            if (!is_string($extension)) {
+                throw new InvalidArgumentException(
+                    sprintf(
+                        'Extension must be a non-empty string, %s provided for %s.',
+                        get_debug_type($extension),
+                        $renderer::class
+                    )
+                );
+            }
+
             if ($extension === '') {
                 throw new InvalidArgumentException(
                     sprintf(
diff --git a/tests/ViewTest.php b/tests/ViewTest.php
index cb4ef35fa..f1c519a11 100644
--- a/tests/ViewTest.php
+++ b/tests/ViewTest.php
@@ -262,6 +262,34 @@ public function testWithRenderersInvalidRendererTypeThrowsException(): void
         ]);
     }
 
+    public function testWithRenderersNumericKeyImplicitThrowsException(): void
+    {
+        $view = TestHelper::createView();
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'Extension must be a non-empty string, int provided for ' . PhpTemplateRenderer::class . '.'
+        );
+
+        $view->withRenderers([
+            new PhpTemplateRenderer(),
+        ]);
+    }
+
+    public function testWithRenderersNumericKeyExplicitThrowsException(): void
+    {
+        $view = TestHelper::createView();
+
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage(
+            'Extension must be a non-empty string, int provided for ' . PhpTemplateRenderer::class . '.'
+        );
+
+        $view->withRenderers([
+            0 => new PhpTemplateRenderer(),
+        ]);
+    }
+
     public function testLocalize(): void
     {
         $view = $this->createViewWithBasePath($this->tempDirectory);
@@ -628,7 +656,7 @@ public function testImmutability(): void
         $view = TestHelper::createView();
 
         $this->assertNotSame($view, $view->withBasePath(''));
-        $this->assertNotSame($view, $view->withRenderers([new PhpTemplateRenderer()]));
+        $this->assertNotSame($view, $view->withRenderers(['php' => new PhpTemplateRenderer()]));
         $this->assertNotSame($view, $view->withSourceLocale('en'));
         $this->assertNotSame($view, $view->withContext($this->createContext($this->tempDirectory)));
         $this->assertNotSame($view, $view->withContextPath(__DIR__));