diff -urp libbraille-0.19.0.orig/backend/baum/brl.c libbraille-0.19.0/backend/baum/brl.c
--- libbraille-0.19.0.orig/backend/baum/brl.c	2006-03-03 18:31:25.000000000 -0600
+++ libbraille-0.19.0/backend/baum/brl.c	2024-04-21 12:02:18.174577670 -0500
@@ -29,8 +29,8 @@
 static char (*drvinit_func) (brli_term *term, const char *pathname);
 static char (*drvclose_func) (brli_term *term);
 static int (*write_func) (brli_term *term, char *bytes, int size);
-static int (*read_byte_func) (brli_term *term, char *byte, int timeout);
-static int (*read_bytes_func) (brli_term *term, char *bytes, int size, int timeout);
+static int (*read_byte_func) (brli_term *term, unsigned char *byte, int timeout);
+static int (*read_bytes_func) (brli_term *term, unsigned char *bytes, int size, int timeout);
 
 #define ESCAPE 0x1B
 #define TSP_DATA_SIZE 5