diff --git a/web/src/main/java/org/springframework/security/web/util/matcher/RequestMatcher.java b/web/src/main/java/org/springframework/security/web/util/matcher/RequestMatcher.java
index c624d4b63f2..c86c2475de7 100644
--- a/web/src/main/java/org/springframework/security/web/util/matcher/RequestMatcher.java
+++ b/web/src/main/java/org/springframework/security/web/util/matcher/RequestMatcher.java
@@ -28,6 +28,7 @@
  * @author Eddú Meléndez
  * @since 3.0.2
  */
+@FunctionalInterface
 public interface RequestMatcher {
 
 	/**