--- a/util-src/hashes.c	Sat Jan 14 14:09:33 2023 +0100
+++ b/util-src/hashes.c	Tue Jan 17 15:30:28 2023 +0100
@@ -229,7 +229,7 @@
 
 	size_t input_len, salt_len, info_len;
 	size_t actual_out_len = luaL_checkinteger(L, 1);
-	const char *input = luaL_checklstring(L, 2, &input_len);
+	const unsigned char *input = (unsigned char *)luaL_checklstring(L, 2, &input_len);
 	const unsigned char *salt = (unsigned char *)luaL_optlstring(L, 3, NULL, &salt_len);
 	const unsigned char *info = (unsigned char *)luaL_checklstring(L, 4, &info_len);