.../lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php     |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
index b9105de..8ef4822 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
@@ -74,7 +74,7 @@ function setUp() {
    * Tests removal of images having a non-local source.
    */
   function testImageSource() {
-    global $base_url;
+    global $base_url, $base_root;
 
     $public_files_path = PublicStream::basePath();
 
@@ -95,10 +95,13 @@ function testImageSource() {
     // Create a list of test image sources.
     // The keys become the value of the IMG 'src' attribute, the values are the
     // expected filter conversions.
+    $test_environment_parts = parse_url($http_base_url);
     $images = array(
       $http_base_url . '/' . $druplicon => base_path() . $druplicon,
-      // Test a url that includes the port.
-      str_replace(base_path(), ':80' . base_path(), $http_base_url) . '/' . $druplicon => base_path() . $druplicon,
+      // Test a url that includes the port; if the current testing environment
+      // does not contain a port, then it must be using port 80 and we can
+      // generate an equivalent URL that does contain it.
+      ((isset($test_environment_parts['port'])) ? $http_base_url : $base_root . ':80' . base_path()) . '/' . $druplicon => base_path() . $druplicon,
       $https_base_url . '/' . $druplicon => base_path() . $druplicon,
       base_path() . $druplicon => base_path() . $druplicon,
       $files_path . '/' . $test_image => $files_path . '/' . $test_image,