--- a/src/chess/rules.h	Fri Apr 17 13:17:34 2026 +0200
+++ b/src/chess/rules.h	Fri Apr 17 14:08:10 2026 +0200
@@ -263,7 +263,7 @@
  * @param str the target buffer (should be at least 10 chars large)
  * @param always_hours if hours should always be printed
  */
-void print_clk(uint16_t time, char *str, bool always_hours);
+int print_clk(uint16_t time, char *str, bool always_hours);
 
 #endif	/* RULES_H */