diff --git a/core/modules/filter/filter.module b/core/modules/filter/filter.module
index ea98965..5f174b3 100644
--- a/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -1390,7 +1390,8 @@ function _filter_html_image_secure_process($text) {
     // Remove absolute URLs pointing to the local domain to prevent mixed
     // content errors.
     $request = \Drupal::request();
-    $image->setAttribute('src', preg_replace('|^https?://' . $request->getHost() . '|', '', $src));
+    $port = $request->getPort();
+    $image->setAttribute('src', preg_replace('|^https?://' . $request->getHost() . '(' . preg_quote(':' . $port) . ')?|', '', $src));
 
     // Verify that $src starts with $base_path.
     // This also ensures that external images cannot be referenced.
diff --git a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
index d61bfa1..b905a30 100644
--- a/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
+++ b/core/modules/filter/lib/Drupal/filter/Tests/FilterHtmlImageSecureTest.php
@@ -97,6 +97,8 @@ function testImageSource() {
     // expected filter conversions.
     $images = array(
       $http_base_url . '/' . $druplicon => base_path() . $druplicon,
+      // Test a url that includes the port.
+      $http_base_url . ':' . $this->container->get('request')->getPort() . 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,