diff --git a/core/modules/workflows/src/Plugin/WorkflowTypeBase.php b/core/modules/workflows/src/Plugin/WorkflowTypeBase.php
index 5810938d..e7c37a62 100644
--- a/core/modules/workflows/src/Plugin/WorkflowTypeBase.php
+++ b/core/modules/workflows/src/Plugin/WorkflowTypeBase.php
@@ -7,6 +7,7 @@
 use Drupal\workflows\State;
 use Drupal\workflows\StateInterface;
 use Drupal\workflows\Transition;
+use Drupal\workflows\TransitionInterface;
 use Drupal\workflows\WorkflowInterface;
 use Drupal\workflows\WorkflowTypeInterface;
 
@@ -314,7 +315,7 @@ public function hasTransition($transition_id) {
   /**
    * {@inheritdoc}
    */
-  public function getTransitionsForState($state_id, $direction = 'from') {
+  public function getTransitionsForState($state_id, $direction = TransitionInterface::DIRECTION_FROM) {
     $transition_ids = array_keys(array_filter($this->configuration['transitions'], function ($transition) use ($state_id, $direction) {
       return in_array($state_id, (array) $transition[$direction], TRUE);
     }));
diff --git a/core/modules/workflows/src/WorkflowTypeInterface.php b/core/modules/workflows/src/WorkflowTypeInterface.php
index 5d5439d7..134e2b1f 100644
--- a/core/modules/workflows/src/WorkflowTypeInterface.php
+++ b/core/modules/workflows/src/WorkflowTypeInterface.php
@@ -248,8 +248,12 @@ public function getTransitions(array $transition_ids = NULL);
    * @param $state_id
    *   The state to get transitions for.
    * @param string $direction
-   *   (optional) The direction of the transition. Defaults to 'from'. Possible
-   *   values are: 'from' and 'to'.
+   *   (optional) The direction of the transition. Defaults to
+   *   \Drupal\workflows\TransitionInterface\TransitionInterface::DIRECTION_FROM.
+   *   Possible values are:
+   *   \Drupal\workflows\TransitionInterface\TransitionInterface::DIRECTION_FROM
+   *   or
+   *   \Drupal\workflows\TransitionInterface\TransitionInterface::DIRECTION_TO.
    *
    * @return array
    *   The transition IDs for a state for the provided direction.