diff --git a/CRM/Civicase/Hook/Tokens/AddCaseCustomFieldsTokenValues.php b/CRM/Civicase/Hook/Tokens/AddCaseCustomFieldsTokenValues.php
index 405e9dbd0..57c2c563e 100644
--- a/CRM/Civicase/Hook/Tokens/AddCaseCustomFieldsTokenValues.php
+++ b/CRM/Civicase/Hook/Tokens/AddCaseCustomFieldsTokenValues.php
@@ -68,7 +68,7 @@ public static function evaluateCaseCustomFieldsTokens(TokenValueEvent $e) {
    * Detects the token activity is triggered by webform.
    */
   private static function isWebform() {
-    return isset($_POST['form_id']) && stripos($_POST['form_id'], 'webform_client_form_');
+    return isset($_POST['form_id']) && stripos($_POST['form_id'], 'webform_client_form_') !== FALSE;
   }
 
 }