diff --git a/cryptfs.h b/cryptfs.h
index 5c05001..352a576 100644
--- a/cryptfs.h
+++ b/cryptfs.h
@@ -228,7 +228,7 @@
                           unsigned char *ikey, void *params);
 
   int cryptfs_crypto_complete(void);
-  int cryptfs_check_passwd(char *pw);
+  int cryptfs_check_passwd(const char *pw);
   int cryptfs_verify_passwd(char *newpw);
   int cryptfs_restart(void);
   int cryptfs_enable(char *flag, int type, char *passwd, int no_ui);