diff --git a/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapEnsureTablesTest.php b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapEnsureTablesTest.php
index d771ab1..93e8476 100644
--- a/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapEnsureTablesTest.php
+++ b/core/modules/migrate/tests/src/Unit/MigrateSqlIdMapEnsureTablesTest.php
@@ -111,6 +111,10 @@ public function testEnsureTablesNotExist() {
     );
     $table_schema['indexes']['sourcekey'] = array('sourceid1');
 
+    $schema->expects($this->at(2))
+      ->method('tableExists')
+      ->with('migrate_message_sql_idmap_test')
+      ->will($this->returnValue(FALSE));
     $schema->expects($this->at(3))
       ->method('createTable')
       ->with('migrate_message_sql_idmap_test', $table_schema);
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
index 23b5570..8a93240 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateDrupal6Test.php
@@ -189,12 +189,14 @@ protected function setUp() {
     // Install one of D8's test themes.
     \Drupal::service('theme_handler')->install(array('test_theme'));
 
-    // Create a new user. This is needed by
-    // \Drupal\migrate_drupal\Tests\d6\MigrateNodeTestBase
+    // Create a new user which needs to have UID 1, because that is expected by
+    // the assertions from
+    // \Drupal\migrate_drupal\Tests\d6\MigrateNodeRevisionTest.
     User::create([
+      'uid' => 1,
       'name' => $this->randomMachineName(),
       'status' => 1,
-    ])->save();
+    ])->enforceIsNew(TRUE)->save();
   }
 
   /**
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateNodeTestBase.php b/core/modules/migrate_drupal/src/Tests/d6/MigrateNodeTestBase.php
index ff36ceb..4ff3ae3 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateNodeTestBase.php
+++ b/core/modules/migrate_drupal/src/Tests/d6/MigrateNodeTestBase.php
@@ -29,11 +29,15 @@ protected function setUp() {
     $this->installSchema('node', ['node_access']);
     $this->installSchema('system', ['sequences']);
 
-    // Create a new user.
+    // Create a new user which needs to have UID 1, because that is expected by
+    // the assertions from
+    // \Drupal\migrate_drupal\Tests\d6\MigrateNodeRevisionTest.
     User::create([
+      'uid' => 1,
       'name' => $this->randomMachineName(),
       'status' => 1,
-    ])->save();
+    ])->enforceIsNew(TRUE)->save();
+
 
     $node_type = entity_create('node_type', array('type' => 'test_planet'));
     $node_type->save();