diff -r 942a0cef9ff5 -r 7e3f2d462bb6 src/chess/rules.h
--- a/src/chess/rules.h	Sat Jul 18 21:18:07 2026 +0200
+++ b/src/chess/rules.h	Sat Jul 18 21:18:38 2026 +0200
@@ -334,7 +334,8 @@
  * @param color the color of the player to evaluate the move for
  * @return status code (see macros in this file for the list of codes)
  */
-int eval_move(GameState *gamestate, char *mstr, Move *move, uint8_t color);
+int eval_move(GameState *gamestate, const char *mstr,
+        Move *move, uint8_t color);
 
 /**
  * Syntactically checks a move without verifying that a piece exists that is
@@ -344,7 +345,7 @@
  * @param color the color of the player to evaluate the move for
  * @return status code (see macros in this file for the list of codes)
  */
-int check_move(char *mstr, uint8_t color);
+int check_move(const char *mstr, uint8_t color);
 
 /**
  * Validates move by applying chess rules.