diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCacheTagsTest.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCacheTagsTest.php
index 6270631..3dacea5 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCacheTagsTest.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Tests/CustomBlockCacheTagsTest.php
@@ -29,7 +29,7 @@ public static function getInfo() {
   /**
    * {@inheritdoc}
    */
-  protected static function createEntity() {
+  protected function createEntity() {
     // Create a "Llama" custom block.
     $custom_block = entity_create('custom_block', array(
       'info' => 'Llama',
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentCacheTagsTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentCacheTagsTest.php
index d42ec20..f14ed3a 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentCacheTagsTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentCacheTagsTest.php
@@ -42,7 +42,7 @@ public function setUp() {
   /**
    * {@inheritdoc}
    */
-  protected static function createEntity() {
+  protected function createEntity() {
     // Create a "bar" bundle for the "entity_test" entity type and create.
     $bundle = 'bar';
     entity_test_create_bundle($bundle, NULL, 'entity_test');
diff --git a/core/modules/node/lib/Drupal/node/Tests/NodeCacheTagsTest.php b/core/modules/node/lib/Drupal/node/Tests/NodeCacheTagsTest.php
index 514c2d9..ec66dae 100644
--- a/core/modules/node/lib/Drupal/node/Tests/NodeCacheTagsTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeCacheTagsTest.php
@@ -43,7 +43,7 @@ public function setUp() {
   /**
    * {@inheritdoc}
    */
-  protected static function createEntity() {
+  protected function createEntity() {
     // Create a "Camelids" node type.
     entity_create('node_type', array(
       'name' => 'Camelids',
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityCacheTagsTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityCacheTagsTestBase.php
index a83ec32..391d81b 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityCacheTagsTestBase.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityCacheTagsTestBase.php
@@ -58,7 +58,7 @@ public function setUp() {
     $user_role->save();
 
     // Create an entity.
-    $this->entity = static::createEntity();
+    $this->entity = $this->createEntity();
 
     // If this is a fieldable entity, then add a configurable field. We will use
     // this configurable field in later tests to ensure that modifications to
@@ -125,14 +125,7 @@ protected static function generateStandardizedInfo($entity_type_label, $group) {
    * @return \Drupal\Core\Entity\EntityInterface
    *   The entity to be tested.
    */
-  protected static function createEntity() {
-    // PHP doesn't allow us to declare this method as abstract protected static,
-    // so we simply throw an exception here if this has not been implemented by
-    // a child class.
-    throw new \RuntimeException(String::format('@class must implement \Drupal\system\Tests\Entity\EntityCacheTagsTestBase::createEntity().', array(
-      '@class' => get_called_class(),
-    )));
-  }
+  abstract protected function createEntity();
 
   /**
    * Creates a referencing and a non-referencing entity for testing purposes.
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermCacheTagsTest.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermCacheTagsTest.php
index 6d7b649..b69df44 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermCacheTagsTest.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermCacheTagsTest.php
@@ -29,7 +29,7 @@ public static function getInfo() {
   /**
    * {@inheritdoc}
    */
-  protected static function createEntity() {
+  protected function createEntity() {
     // Create a "Camelids" vocabulary.
     $vocabulary = entity_create('taxonomy_vocabulary',  array(
       'name' => 'Camelids',
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserCacheTagsTest.php b/core/modules/user/lib/Drupal/user/Tests/UserCacheTagsTest.php
index 8db5b7b..6d0497e 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserCacheTagsTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserCacheTagsTest.php
@@ -42,7 +42,7 @@ public function setUp() {
   /**
    * {@inheritdoc}
    */
-  protected static function createEntity() {
+  protected function createEntity() {
     // Create a "Llama" user.
     $user = entity_create('user', array(
       'name' => 'Llama',