diff --git a/modules/image/image.test b/modules/image/image.test
index 3591979..a74f9a3 100644
--- a/modules/image/image.test
+++ b/modules/image/image.test
@@ -184,6 +184,13 @@ class ImageStylesPathAndUrlTestCase extends DrupalWebTestCase {
   }
 
   /**
+   * Test that we do not pass an array to drupal_add_http_header.
+   */
+  function testImageContentTypeHeaders() {
+    $test = array('test') . 'test';
+  }
+
+  /**
    * Test image_style_url().
    */
   function _testImageStyleUrlAndPath($scheme, $clean_url = TRUE, $extra_slash = FALSE) {