diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 162a833..8a9bf9f 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1768,7 +1768,7 @@ function template_preprocess_image(&$variables) {
   $variables['attributes']['src'] = file_create_url($variables['uri']);
 
   foreach (array('width', 'height', 'alt', 'title') as $key) {
-    if (!empty($variables[$key])) {
+    if (isset($variables[$key])) {
       $variables['attributes'][$key] = $variables[$key];
     }
   }
diff --git a/core/modules/image/lib/Drupal/image/Tests/ImageThemeFunctionTest.php b/core/modules/image/lib/Drupal/image/Tests/ImageThemeFunctionTest.php
index 9339685..6185f15 100644
--- a/core/modules/image/lib/Drupal/image/Tests/ImageThemeFunctionTest.php
+++ b/core/modules/image/lib/Drupal/image/Tests/ImageThemeFunctionTest.php
@@ -56,17 +56,15 @@ function testImageFormatterTheme() {
         'path' => $path,
       ),
     );
-    $rendered_element = render($element);
-    $expected_result = '<a href="' . base_path() . $path . '"><img class="image-style-test" src="' . $url . '" />
-</a>';
-    $this->assertEqual($expected_result, $rendered_element, 'theme_image_formatter() correctly renders with a NULL value for the alt option.');
+    $this->drupalSetContent(render($element));
+    $elements = $this->xpath('//a[@href=:path]/img[@class="image-style-test" and @src=:url]', array(':path' => base_path() . $path, ':url' => $url));
+    $this->assertEqual(count($elements), 1, 'theme_image_formatter() correctly renders with a NULL value for the alt option.');
 
     // Test using theme_image_formatter() without an image title, alt text, or
     // link options.
     unset($element['#item']['alt']);
     $this->drupalSetContent(render($element));
-    $rendered_element = render($element);
-    $elements = $this->xpath('//a[@href=:path]/img[@class="image-style-test" and @src=:url]', array(':path' => base_path() . $path, ':url' => $url));
+    $elements = $this->xpath('//a[@href=:path]/img[@class="image-style-test" and @src=:url and @alt=""]', array(':path' => base_path() . $path, ':url' => $url));
     $this->assertEqual(count($elements), 1, 'theme_image_formatter() correctly renders without title, alt, or path options.');
 
     // Link the image to a fragment on the page, and not a full URL.
@@ -78,7 +76,7 @@ function testImageFormatterTheme() {
     );
 
     $this->drupalSetContent(render($element));
-    $elements = $this->xpath('//a[@href=:fragment]/img[@class="image-style-test" and @src=:url]', array(':fragment' => '#' . $fragment, ':url' => $url));
+    $elements = $this->xpath('//a[@href=:fragment]/img[@class="image-style-test" and @src=:url and @alt=""]', array(':fragment' => '#' . $fragment, ':url' => $url));
     $this->assertEqual(count($elements), 1, 'theme_image_formatter() correctly renders a link fragment.');
   }
 
@@ -103,15 +101,14 @@ function testImageStyleTheme() {
       '#uri' => $original_uri,
     );
     $this->drupalSetContent(render($element));
-    $elements = $this->xpath('//img[@class="image-style-image-test" and @src=:url]', array(':url' => $url));
+    $elements = $this->xpath('//img[@class="image-style-image-test" and @src=:url and @alt=""]', array(':url' => $url));
     $this->assertEqual(count($elements), 1, 'theme_image_style() renders an image correctly.');
 
     // Test using theme_image_style() with a NULL value for the alt option.
     $element['#alt'] = NULL;
-    $rendered_element = render($element);
-    $expected_result = '<img class="image-style-image-test" src="' . $url . '" />
-';
-    $this->assertEqual($expected_result, $rendered_element, 'theme_image_style() renders an image correctly with a NULL value for the alt option.');
+    $this->drupalSetContent(render($element));
+    $elements = $this->xpath('//img[@class="image-style-image-test" and @src=:url]', array(':url' => $url));
+    $this->assertEqual(count($elements), 1, 'theme_image_style() renders an image correctly with a NULL value for the alt option.');
   }
 
 }