diff --git a/core/modules/file/src/Tests/FileManagedFileElementTest.php b/core/modules/file/src/Tests/FileManagedFileElementTest.php
index 1bd46c0..61c00de 100644
--- a/core/modules/file/src/Tests/FileManagedFileElementTest.php
+++ b/core/modules/file/src/Tests/FileManagedFileElementTest.php
@@ -124,7 +124,7 @@ function testManagedFile() {
               $edit = array($file_field_name => $file_system->realpath('public://test.dat'));
               if ($ajax) {
                 $this->drupalPostAjaxForm(NULL, $edit, $input_base_name . '_upload_button');
-                $this->assertText(SafeMarkup::format('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@post_max_size) that this server supports.', ['@post_max_size' => $post_max_size_init]));
+                $this->assertText(SafeMarkup::format('An unrecoverable error occurred. The uploaded file likely exceeded the maximum file size (@post_max_size) that this server supports.', ['@post_max_size' => format_size(file_upload_max_size())]));
               }
               else {
                 // @todo Currently the post request just fails, as there is no
diff --git a/core/modules/system/src/Tests/Ajax/AjaxFormCacheTest.php b/core/modules/system/src/Tests/Ajax/AjaxFormCacheTest.php
index 8c29a74..a35b709 100644
--- a/core/modules/system/src/Tests/Ajax/AjaxFormCacheTest.php
+++ b/core/modules/system/src/Tests/Ajax/AjaxFormCacheTest.php
@@ -64,7 +64,7 @@ public function testBlockForms() {
     $this->drupalPostAjaxForm(NULL, ['test1' => 'option1'], 'test1');
     $this->assertOptionSelected('edit-test1--2', 'option1');
     $this->assertOption('edit-test1--2', 'option3');
-    $this->drupalPostForm($this->getUrl(), ['test1' => 'option1'], 'Submit');
+    $this->drupalPostForm(NULL, ['test1' => 'option1'], 'Submit');
     $this->assertText('Submission successful.');
   }