diff --git a/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php b/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
index 4bb30e2..3040bab 100644
--- a/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
+++ b/core/lib/Drupal/Core/Entity/Sql/DefaultTableMapping.php
@@ -606,16 +606,16 @@ public function getDedicatedRevisionTableName(FieldStorageDefinitionInterface $s
   protected function generateFieldTableName(FieldStorageDefinitionInterface $storage_definition, $revision) {
     $separator = $revision ? '_revision__' : '__';
     $table_name = $this->prefix . $storage_definition->getTargetEntityTypeId() . $separator . $storage_definition->getName();
-    // Limit the string to 48 characters, keeping a 16 characters margin for db
-    // prefixes.
-    if (strlen($table_name) > 48) {
+    // Limit the string to 48 characters minus the prefix length, keeping a 16
+    // characters margin for db prefixes.
+    if (strlen($table_name) > 48 - strlen($this->prefix)) {
       // Use a shorter separator, a truncated entity_type, and a hash of the
       // field storage unique identifier.
       $separator = $revision ? '_r__' : '__';
       // Truncate to the same length for the current and revision tables.
       $entity_type = substr($storage_definition->getTargetEntityTypeId(), 0, 34);
       $field_hash = substr(hash('sha256', $storage_definition->getUniqueStorageIdentifier()), 0, 10);
-      $table_name = $entity_type . $separator . $field_hash;
+      $table_name = $this->prefix . $entity_type . $separator . $field_hash;
     }
     return $table_name;
   }
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
index ae41289..966aa00 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -303,7 +303,6 @@ public function setTableMapping(TableMappingInterface $table_mapping) {
    */
   public function setTemporary($temporary) {
     $this->temporary = $temporary;
-    $this->initTableLayout();
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
index d2c0471..58e66a9 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchemaConverter.php
@@ -158,8 +158,9 @@ public function convertToRevisionable(array &$sandbox, array $fields_to_update =
       // storage definitions.
       try {
         $storage = $this->entityTypeManager->getStorage($this->entityTypeId);
+        $storage->setEntityType($actual_entity_type);
         $storage->setTemporary(FALSE);
-        $actual_table_names = $storage->getTableMapping($sandbox['updated_storage_definitions'], $actual_entity_type)->getTableNames();
+        $actual_table_names = $storage->getCustomTableMapping($actual_entity_type, $sandbox['updated_storage_definitions'])->getTableNames();
 
         $table_name_mapping = [];
         foreach ($actual_table_names as $new_table_name) {
@@ -491,7 +492,7 @@ protected function createTemporaryDefinitions(array &$sandbox, array $fields_to_
     /** @var \Drupal\Core\Entity\Sql\SqlContentEntityStorage $storage */
     $storage = $this->entityTypeManager->getStorage($this->entityTypeId);
     $storage->setTemporary(TRUE);
-    $temporary_table_mapping = $storage->getTableMapping($updated_storage_definitions, $temporary_entity_type);
+    $temporary_table_mapping = $storage->getCustomTableMapping($temporary_entity_type, $updated_storage_definitions);
 
     $sandbox['temporary_entity_type'] = $temporary_entity_type;
     $sandbox['temporary_table_mapping'] = $temporary_table_mapping;
@@ -514,9 +515,9 @@ protected function createTemporaryDefinitions(array &$sandbox, array $fields_to_
   public static function getPrefixedTableName($table_name, $prefix) {
     $prefixed_table_name = $prefix . $table_name;
 
-    // Limit the string to 48 characters, keeping a 16 characters margin for db
-    // prefixes.
-    if (strlen($table_name) > 48) {
+    // Limit the string to 48 characters minus the length of the prefix, keeping
+    // a 16 characters margin for db prefixes.
+    if (strlen($table_name) > 48 - strlen($prefix)) {
       $short_table_name = substr($table_name, 0, 34);
       $table_hash = substr(hash('sha256', $table_name), 0, 10);
 
diff --git a/core/modules/system/tests/modules/entity_test_update/src/EntityTestUpdateStorageSchema.php b/core/modules/system/tests/modules/entity_test_update/src/EntityTestUpdateStorageSchema.php
index 2b75e83..b1d92d0 100644
--- a/core/modules/system/tests/modules/entity_test_update/src/EntityTestUpdateStorageSchema.php
+++ b/core/modules/system/tests/modules/entity_test_update/src/EntityTestUpdateStorageSchema.php
@@ -18,7 +18,7 @@ protected function getEntitySchema(ContentEntityTypeInterface $entity_type, $res
     $schema = parent::getEntitySchema($entity_type, $reset);
 
     if ($entity_type->id() == 'entity_test_update') {
-      $schema[$entity_type->getBaseTable()]['indexes'] += \Drupal::state()->get('entity_test_update.additional_entity_indexes', []);
+      $schema[$this->storage->getTableMapping()->getBaseTable()]['indexes'] += \Drupal::state()->get('entity_test_update.additional_entity_indexes', []);
     }
     return $schema;
   }