diff --git a/security/voters.rst b/security/voters.rst
index d96be9bf6c4..528a654eb17 100644
--- a/security/voters.rst
+++ b/security/voters.rst
@@ -56,8 +56,8 @@ which makes creating a voter even easier::
 
     abstract class Voter implements VoterInterface
     {
-        abstract protected function supports($attribute, $subject);
-        abstract protected function voteOnAttribute($attribute, $subject, TokenInterface $token);
+        abstract protected function supports($attribute, $subject): bool;
+        abstract protected function voteOnAttribute($attribute, $subject, TokenInterface $token): bool;
     }
 
 .. _how-to-use-the-voter-in-a-controller: