diff --git a/src/cat.c b/src/cat.c
index aebd69e..81667de 100644
--- a/src/cat.c
+++ b/src/cat.c
@@ -24,8 +24,9 @@ static int _cat_error(char * message, int ret);
 static void _cat_file(FILE * fp, OutputDelay od);
 static int _cat(OutputDelay od, int argc, char * argv[])
 {
-	int res = 0;
+	int ret = 0;
 	int i;
+	FILE * fp;
 
 	if(argc == 0)
 	{
@@ -34,20 +35,18 @@ static int _cat(OutputDelay od, int argc, char * argv[])
 	}
 	for(i = 0; i < argc; i++)
 	{
-		FILE * fp;
-
 		if(strcmp("-", argv[i]) == 0)
 			fp = stdin;
 		else if((fp = fopen(argv[i], "r")) == NULL)
 		{
-			res = _cat_error(argv[i], 2);
+			ret = _cat_error(argv[i], 1);
 			continue;
 		}
 		_cat_file(fp, od);
 		if(fp != stdin)
 			fclose(fp);
 	}
-	return res;
+	return ret;
 }
 
 static int _cat_error(char * message, int ret)
@@ -83,7 +82,7 @@ static int _write_nonbuf(int c)
 /* usage */
 static int _usage(void)
 {
-	fprintf(stderr, "Usage: cat [-u][file ...]\n\
+	fprintf(stderr, "%s", "Usage: cat [-u][file ...]\n\
   -u    write without delay\n");
 	return 1;
 }
@@ -101,7 +100,7 @@ int main(int argc, char * argv[])
 			case 'u':
 				flagu = OD_NONE;
 				break;
-			case '?':
+			default:
 				return _usage();
 		}
 	return _cat(flagu, argc - optind, &argv[optind]);
diff --git a/src/mkfifo.c b/src/mkfifo.c
index 95fe8de..7ae63c3 100644
--- a/src/mkfifo.c
+++ b/src/mkfifo.c
@@ -36,7 +36,7 @@ static int _mkfifo_error(char * message, int ret)
 /* usage */
 static int _usage(void)
 {
-	fprintf(stderr, "Usage: mkfifo [-m mode] file...\n\
+	fprintf(stderr, "%s", "Usage: mkfifo [-m mode] file...\n\
   -m	create fifo with the specified mode value\n");
 	return 1;
 }
diff --git a/src/pwd.c b/src/pwd.c
index f29e4d9..dcdf2ad 100644
--- a/src/pwd.c
+++ b/src/pwd.c
@@ -72,7 +72,7 @@ static int _pwd(pwd_flag pf)
 /* usage */
 static int _usage(void)
 {
-	fprintf(stderr, "Usage: pwd [-L|-P]\n\
+	fprintf(stderr, "%s", "Usage: pwd [-L|-P]\n\
   -L    avoid \".\" or \"..\" filenames\n\
   -P    avoid symbolic links\n");
 	return 1;
diff --git a/src/rmdir.c b/src/rmdir.c
index bcffc45..9e8518d 100644
--- a/src/rmdir.c
+++ b/src/rmdir.c
@@ -54,7 +54,7 @@ static int _rmdir_p(char * pathname)
 /* usage */
 static int _usage(void)
 {
-	fprintf(stderr, "Usage: rmdir [-p] dir...\n\
+	fprintf(stderr, "%s", "Usage: rmdir [-p] dir...\n\
   -p    remove all directories in a pathname\n");
 	return 1;
 }
diff --git a/src/uname.c b/src/uname.c
index 2f91c6f..4cbb5e1 100644
--- a/src/uname.c
+++ b/src/uname.c
@@ -38,7 +38,7 @@ static int _uname(int m, int n, int r, int s, int v)
 /* usage */
 static int _usage(void)
 {
-	fprintf(stderr, "Usage: uname [-snrvma]\n\
+	fprintf(stderr, "%s", "Usage: uname [-snrvma]\n\
   -s    operating system name\n\
   -n    name of this node on the network\n\
   -r    operating system release name\n\