diff --git a/password_policy_character_types/src/Plugin/PasswordConstraint/CharacterTypes.php b/password_policy_character_types/src/Plugin/PasswordConstraint/CharacterTypes.php
index fa03de3..f6ad690 100644
--- a/password_policy_character_types/src/Plugin/PasswordConstraint/CharacterTypes.php
+++ b/password_policy_character_types/src/Plugin/PasswordConstraint/CharacterTypes.php
@@ -5,7 +5,6 @@
  * Contains Drupal\password_policy_character_types\Constraints\CharacterTypes.
  */
 
-
 namespace Drupal\password_policy_character_types\Plugin\PasswordConstraint;
 
 use Drupal\Core\Form\FormStateInterface;
@@ -13,7 +12,7 @@ use Drupal\password_policy\PasswordConstraintBase;
 use Drupal\password_policy\PasswordPolicyValidation;
 
 /**
- * Enforces a specific character length for passwords. <-- FIXME
+ * Enforces a minimum number of character types for passwords.
  *
  * @PasswordConstraint(
  *   id = "character_types",
@@ -27,10 +26,10 @@ class CharacterTypes extends PasswordConstraintBase {
   /**
    * {@inheritdoc}
    */
-  function validate($password, $user_context) {
+  public function validate($password, $user_context) {
     $validation = new PasswordPolicyValidation();
     $types = $this->getConfiguration()['character_types'];
-    if ($types > 4 || $types < 1) {
+    if ($types < 2 || $types > 4) {
       $validation->setErrorMessage($this->t('Invalid plugin configuration.'));
     }
     $character_sets = count(array_filter([
@@ -40,7 +39,7 @@ class CharacterTypes extends PasswordConstraintBase {
       preg_match('[^a-zA-Z0-9]', $password),
     ]));
     if ($character_sets < $types) {
-      $validation->setErrorMessage($this->t('The password is required to contain at least @types types of characters from the character sets: lowercase alphabetic characters (a–z), uppercase alphabetic characters (A–Z), numeric characters (0–9), special characters.', ['@types' => $types]));
+      $validation->setErrorMessage($this->t('The password is required to contain at least @types types of characters from the character types: lowercase alphabetic characters (a–z), uppercase alphabetic characters (A–Z), numeric characters (0–9), special characters.', ['@types' => $types]));
     }
     return $validation;
   }
@@ -61,7 +60,7 @@ class CharacterTypes extends PasswordConstraintBase {
     $form['character_types'] = [
       '#type' => 'number',
       '#title' => $this->t('Number of character types'),
-      '#description' => $this->t('Select the number of character sets which must be found in a password. The supported character sets are given as: lowercase alphabetic characters (a–z), uppercase alphabetic characters (A–Z), numeric characters (0–9), special characters.'),
+      '#description' => $this->t('Select the minimum number of character types which must be found in a password. The four supported character types are given as: lowercase alphabetic characters (a–z), uppercase alphabetic characters (A–Z), numeric characters (0–9), special characters.'),
       '#default_value' => $this->getConfiguration()['character_types'],
     ];
     return $form;
@@ -72,8 +71,8 @@ class CharacterTypes extends PasswordConstraintBase {
    */
   public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
     $types = $form_state->getValue('character_types');
-    if (!is_numeric($types) || $types < 1 || $types > 4) {
-      $form_state->setErrorByName('character_types', $this->t('The number of character types must be between 1 and 4.'));
+    if (!is_numeric($types) || $types < 2 || $types > 4) {
+      $form_state->setErrorByName('character_types', $this->t('The number of character types must be between 2 and 4.'));
     }
   }
 
diff --git a/password_policy_character_types/tests/src/Unit/CharacterTypesTest.php b/password_policy_character_types/tests/src/Unit/CharacterTypesTest.php
index 79dc003..5ebf661 100644
--- a/password_policy_character_types/tests/src/Unit/CharacterTypesTest.php
+++ b/password_policy_character_types/tests/src/Unit/CharacterTypesTest.php
@@ -1,5 +1,10 @@
 <?php
 
+/**
+ * @file
+ * Contains \Drupal\Tests\password_policy_character_types\Unit.
+ */
+
 namespace Drupal\Tests\password_policy_character_types\Unit;
 
 use Drupal\Tests\UnitTestCase;
@@ -92,4 +97,5 @@ class CharacterTypesTest extends UnitTestCase {
       ],
     ];
   }
+
 }