diff -u b/src/Plugin/migrate/process/CallbackPlus.php b/src/Plugin/migrate/process/CallbackPlus.php
--- b/src/Plugin/migrate/process/CallbackPlus.php
+++ b/src/Plugin/migrate/process/CallbackPlus.php
@@ -2,50 +2,57 @@
 
 namespace Drupal\migrate_plus\Plugin\migrate\process;
 
+use Drupal\migrate\MigrateException;
 use Drupal\migrate\MigrateExecutableInterface;
-use Drupal\migrate\ProcessPluginBase;
+use Drupal\migrate\Plugin\migrate\process\Callback;
 use Drupal\migrate\Row;
 
 /**
- * Passes the source value and additional parameters to a callback.
+ * Passes the source value to a callback with additional callback parameters.
  *
- * The callback_plus process plugin allows processing of the value, such
- * as ltrim(), which requires multiple parameters. Cores callback process plugin
- * don't allow to pass multiple parameters. The callable passes the source array
- * as arguments to the callback.
+ * @MigrateProcessPlugin(
+ *   id = "callback_plus"
+ * )
+ *
+ * The callback_plus process plugin allows processing using callback functions
+ * that allow/require additional parameters.
+ *
+ * Only functions that take the 'value' to transform as the first parameter
+ * are currently supported.
  *
- * Available configuration keys:
- * - callable: The name of the callable method.
+ * Example:
  *
- * Examples:
+ * Say you have an url source with slashes (/) added to the end. With rtrim and
+ * '/' as a parameter you can remove the slash and make the url suitable for
+ * Drupal's path aliases.
  *
  * @code
  * process:
  *   destination_field:
  *     plugin: callback_plus
- *     callable: ltrim
- *     source:
- *       - source_field
- *       - constant/character_mask
+ *     callable: rtrim
+ *     parameters:
+ *       - '/'
  * @endcode
  *
- *
  * @see \Drupal\migrate\Plugin\MigrateProcessInterface
  *
- * @MigrateProcessPlugin(
- *   id = "callback_plus"
- * )
  */
-class CallbackPlus extends ProcessPluginBase {
+class CallbackPlus extends Callback {
 
   /**
    * {@inheritdoc}
    */
   public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
-    if (is_callable($this->configuration['callable'])) {
-      $param_arr = is_array($value)? $value : array($value);
-      $value = call_user_func_array($this->configuration['callable'], $param_arr);
+    $parameters = isset($this->configuration['parameters']) ? $this->configuration['parameters'] : [];
+    if(empty($parameters) || !is_array($this->configuration['parameters'])) {
+      throw new MigrateException('The callback plus plugin requires an array of "parameters".');
+    }
+    if(!isset($this->configuration['callable']) || !is_callable($this->configuration['callable'])){
+      throw new MigrateException('The callback plus plugin is missing a valid "callable".');
     }
+    $parameters = array_merge([$value], $parameters);
+    $value = call_user_func_array($this->configuration['callable'], $parameters);
     return $value;
   }
 
only in patch2:
unchanged:
--- /dev/null
+++ b/tests/src/Unit/process/CallbackPlusTest.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace Drupal\Tests\migrate_plus\Unit\process;
+
+use Drupal\migrate_plus\Plugin\migrate\process\CallbackPlus;
+use Drupal\migrate_plus\Plugin\migrate\process\StrReplace;
+use Drupal\Tests\migrate\Unit\process\MigrateProcessTestCase;
+
+/**
+ * Tests the Callback Plus process plugin.
+ *
+ * @group migrate
+ * @coversDefaultClass \Drupal\migrate_plus\Plugin\migrate\process\CallbackPlus
+ */
+class CallbackPlusTest extends MigrateProcessTestCase {
+
+  /**
+   * Test for a rtrim with parameters.
+   */
+  public function testRightTrim() {
+    $value = '/foo/bar/';
+    $configuration['parameters'] = ['/'];
+    $configuration['callable'] = 'rtrim';
+    $plugin = new CallbackPlus($configuration, 'callback_plus', []);
+    $actual = $plugin->transform($value, $this->migrateExecutable, $this->row, 'destinationproperty');
+    $this->assertSame('/foo/bar', $actual);
+  }
+
+  /**
+   * Tests that an exception is thrown when no array of parameters is present.
+   */
+  public function testIncorrectParametersException() {
+    $value = '/foo/bar/';
+    $configuration['parameters'] = 'foo';
+    $configuration['callable'] = 'rtrim';
+    $plugin = new CallbackPlus($configuration, 'callback_plus', []);
+    $this->setExpectedException('\Drupal\migrate\MigrateException', 'The callback plus plugin requires an array of "parameters".');
+    $plugin->transform($value, $this->migrateExecutable, $this->row, 'destinationproperty');
+  }
+
+  /**
+   * Tests that an exception is thrown when callable is not valid.
+   */
+  public function testNonValidCallbale() {
+    $value = '/foo/bar/';
+    $configuration['parameters'] = ['/'];
+    $configuration['callback'] = 'footrim';
+    $plugin = new CallbackPlus($configuration, 'callback_plus', []);
+    $this->setExpectedException('\Drupal\migrate\MigrateException', 'The callback plus plugin is missing a valid "callable".');
+    $plugin->transform($value, $this->migrateExecutable, $this->row, 'destinationproperty');
+  }
+
+}