diff --git a/src/Plugin/TypedDataFilter/InitialDotLastFilter.php b/src/Plugin/TypedDataFilter/InitialDotLastFilter.php
index 06cd8e16..3cd6735f 100644
--- a/src/Plugin/TypedDataFilter/InitialDotLastFilter.php
+++ b/src/Plugin/TypedDataFilter/InitialDotLastFilter.php
@@ -26,7 +26,7 @@ class InitialDotLastFilter extends DataFilterBase {
   /**
    * {@inheritdoc}
    */
-  public function canFilter(DataDefinitionInterface $definition) {
+  public function canFilter(DataDefinitionInterface $definition) : bool {
     if ($definition->getConstraints()['EntityType'] == "civicrm_contact") {
       return TRUE;
     }
@@ -38,7 +38,7 @@ public function canFilter(DataDefinitionInterface $definition) {
   /**
    * {@inheritdoc}
    */
-  public function filtersTo(DataDefinitionInterface $definition, array $arguments) {
+  public function filtersTo(DataDefinitionInterface $definition, array $arguments) : DataDefinitionInterface {
     return DataDefinition::create('string');
   }