diff --git a/tests/file_change_bytes.c b/tests/file_change_bytes.c
index 3a86f92..a725278 100644
--- a/tests/file_change_bytes.c
+++ b/tests/file_change_bytes.c
@@ -1,143 +1,143 @@
 /*
  * Copyright (C) 2013 Red Hat, Inc.
  *
  * All rights reserved.
  *
  * Author: Jan Friesse <jfriesse@redhat.com>
  *
  * libqb is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
  * the Free Software Foundation, either version 2.1 of the License, or
  * (at your option) any later version.
  *
  * libqb is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public License
  * along with libqb.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <sys/types.h>
 
 #include <assert.h>
 #include <err.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
 
 static void usage(void)
 {
 	printf("Usage: [ -i input_file] [ -o output_file ] [ -n no_bytes]\n");
 	printf("Changes no_bytes (default 1024) in input_file (default = - = stdin) and store\n");
 	printf("result to output_file (default = - = stdout). It's possible to use same file\n");
 	printf("as both input and output\n");
 
 	exit(1);
 }
 
 static void init_rand(void) {
 	unsigned int init_v;
 
 	init_v = time(NULL) + getpid();
 
 	srand(init_v);
 }
 
 int main(int argc, char *argv[])
 {
 	FILE *fi, *fo;
 	int i;
-	char *input_file_name;
-	char *output_file_name;
+	const char *input_file_name;
+	const char *output_file_name;
 	int no_bytes;
 	char *ep;
 	int ch;
 	unsigned char *data;
 	size_t data_size;
 	size_t data_pos;
 	size_t input_data_size;
 	unsigned char buf[1024];
 
 	input_file_name = "-";
 	output_file_name = "-";
 	no_bytes = 1024;
 
 	while ((ch = getopt(argc, argv, "hi:o:n:")) != -1) {
 		switch (ch) {
 		case 'i':
 			input_file_name = optarg;
 			break;
 		case 'n':
 			no_bytes = strtol(optarg, &ep, 10);
 			if (no_bytes < 0 || *ep != '\0') {
 				warnx("illegal number -- %s", argv[2]);
 				usage();
 			}
 			break;
 		case 'o':
 			output_file_name = optarg;
 			break;
 		case 'h':
 		case '?':
 		default:
 			usage();
 			/* NOTREACHED */
 		}
 	}
 
 	if (strcmp(input_file_name, "-") == 0) {
 		fi = stdin;
 	} else {
 		fi = fopen(input_file_name, "rb");
 		if (fi == NULL) {
 			err(1, "%s", input_file_name);
 		}
 	}
 
 	/*
 	 * Open and fully read input file
 	 */
 	data = NULL;
 	data_size = 0;
 	data_pos = 0;
 	while ((input_data_size = fread(buf, 1, sizeof(buf), fi)) != 0) {
 		if (data_pos + input_data_size >= data_size) {
 			data_size = (data_size + input_data_size) * 2;
 			assert((data = realloc(data, data_size)) != NULL);
 		}
 		memcpy(data + data_pos, buf, input_data_size);
 		data_pos += input_data_size;
 	}
 	fclose(fi);
 
 	/*
 	 * Change bytes
 	 */
 	init_rand();
 
 	for (i = 0; i < no_bytes; i++) {
 		data[rand() % data_pos] = rand();
 	}
 
 	/*
 	 * Fully write ouput file
 	 */
 	if (strcmp(output_file_name, "-") == 0) {
 		fo = stdout;
 	} else {
 		fo = fopen(output_file_name, "wb");
 		if (fo == NULL) {
 			err(1, "%s", output_file_name);
 		}
 	}
 	assert(fwrite(data, 1, data_pos, fo) == data_pos);
 	fclose(fo);
 
 	free(data);
 
 	return (0);
 }