diff --git a/examples/button.c b/examples/button.c
index 8b86b64..ba0285e 100644
--- a/examples/button.c
+++ b/examples/button.c
@@ -1,3 +1,5 @@
+// Copyright (jacekpoz 2024). Licensed under the EUPL-1.2 or later.
+
 #include <stdlib.h>
 #include <ptk.h>
 #include <ptk_color.h>