diff --git a/src/dj.c b/src/dj.c
index 1913dd9..c4ebf38 100644
--- a/src/dj.c
+++ b/src/dj.c
@@ -146,11 +146,13 @@ parse(char *s) {
 }
 
 static int
-usage(char *s) {
-	fprintf(
-		stderr, "Usage: %s [-Hn] [-a byte] [-c count]\n"
+usage(char *argv0) {
+	(void)fprintf(
+		stderr,
+		"Usage: %s [-Hn] [-a byte] [-c count]\n"
 		"\t[-i file] [-b block_size] [-s offset]\n"
-		"\t[-o file] [-B block_size] [-S offset]\n", s
+		"\t[-o file] [-B block_size] [-S offset]\n",
+		argv0
 	);
 
 	return EX_USAGE;
diff --git a/src/intcmp.c b/src/intcmp.c
index f990a10..35fecf3 100644
--- a/src/intcmp.c
+++ b/src/intcmp.c
@@ -32,8 +32,9 @@
 
 char *program_name = "intcmp";
 
-int usage(char *s) {
-	fprintf(stderr, "Usage: %s [-egl] integer integer...\n", s);
+static int
+usage(char *argv0) {
+	(void)fprintf(stderr, "Usage: %s [-egl] integer integer...\n", argv0);
 
 	return EX_USAGE;
 }
diff --git a/src/mm.c b/src/mm.c
index 1d97ab5..d148446 100644
--- a/src/mm.c
+++ b/src/mm.c
@@ -107,11 +107,13 @@ oserr(char *s, char *r) {
 	} \
 	return retval
 
-/* Prints a usage text, in which s is the program being run (i.e. argv[0]), and
- * returns an exit status appropriate for a usage error. */
-int usage(char *s) {
-
-	fprintf(stderr, "Usage: %s [-aenu] [-i input]... [-o output]...\n", s);
+static int
+usage(char *argv0) {
+	(void)fprintf(
+		stderr,
+		"Usage: %s [-aenu] [-i input]... [-o output]...\n",
+		argv0
+	);
 
 	return EX_USAGE;
 }
diff --git a/src/npc.c b/src/npc.c
index 4f74c6f..4cc4160 100644
--- a/src/npc.c
+++ b/src/npc.c
@@ -25,8 +25,10 @@
 
 char *program_name = "npc";
 
-int usage(char *s) {
-	fprintf(stderr, "Usage: %s [-et]\n", s);
+static int
+usage(char *argv0) {
+	fprintf(stderr, "Usage: %s [-et]\n", argv0);
+
 	return EX_USAGE;
 }
 
diff --git a/src/scrut.c b/src/scrut.c
index 7320c8f..4d5a932 100644
--- a/src/scrut.c
+++ b/src/scrut.c
@@ -27,15 +27,18 @@
                        * S_ISUID, S_ISVTX */
 
 char *program_name = "scrut";
-static char args[] = "bcdefgkprsuwxLS";
+#define OPTS "bcdefgkprsuwxLS"
+static char *opts = OPTS;
+
+static int
+usage(char *argv0) {
+	(void)fprintf(stderr, "Usage: %s [-" OPTS "] file...\n", argv0);
 
-int usage(char *s) {
-	fprintf(stderr, "Usage: %s [-%s] file...\n", s, args);
 	return EX_USAGE;
 }
 
 int main(int argc, char *argv[]) {
-	char sel[(sizeof args) / (sizeof *args)];
+	char sel[(sizeof opts) / (sizeof *opts)];
 	program_name = (argv[0] == NULL ? program_name : argv[0]);
 
 	if (argc < 2) { return usage(program_name); }
@@ -44,9 +47,9 @@ int main(int argc, char *argv[]) {
 		char *p;
 
 		memset(sel, '\0', sizeof sel);
-		for (int c; (c = getopt(argc, argv, args)) != -1;) {
-			if ((p = strchr(args, c)) == NULL) { return usage(program_name); }
-			else { sel[p - args] = c; }
+		for (int c; (c = getopt(argc, argv, opts)) != -1;) {
+			if ((p = strchr(opts, c)) == NULL) { return usage(program_name); }
+			else { sel[p - opts] = c; }
 		}
 
 		/* straighten out selections; permute out nulls */
diff --git a/src/str.c b/src/str.c
index e503470..a41e4a1 100644
--- a/src/str.c
+++ b/src/str.c
@@ -45,8 +45,10 @@ static struct {
 	{ NULL, NULL } /* marks end */
 };
 
-int usage(char *s){
-	fprintf(stderr, "Usage: %s type string...\n", s);
+static int
+usage(char *argv0){
+	(void)fprintf(stderr, "Usage: %s type string...\n", argv0);
+
 	return EX_USAGE;
 }