diff --git a/lib/libstdbuf/libstdbuf.3 b/lib/libstdbuf/libstdbuf.3
index 6f3256c88e18..4857f7096499 100644
--- a/lib/libstdbuf/libstdbuf.3
+++ b/lib/libstdbuf/libstdbuf.3
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 28, 2012
+.Dd June 29, 2023
 .Dt LIBSTDBUF 3
 .Os
 .Sh NAME
@@ -80,9 +80,12 @@ output will not stall until the full buffer fills.
     STDBUF_1=L awk '$2 > 1 || $3 > 1' | cat -n
 .Ed
 .Pp
-See also the manpage of
+See
 .Xr stdbuf 1
 for a simpler way to do this.
+.Sh SEE ALSO
+.Xr rtld 1 ,
+.Xr stdbuf 1
 .Sh HISTORY
 The
 .Nm
diff --git a/usr.bin/stdbuf/stdbuf.c b/usr.bin/stdbuf/stdbuf.c
index 02716ad60b06..6b09bb6149f5 100644
--- a/usr.bin/stdbuf/stdbuf.c
+++ b/usr.bin/stdbuf/stdbuf.c
@@ -34,22 +34,38 @@
 #define	LIBSTDBUF	"/usr/lib/libstdbuf.so"
 #define	LIBSTDBUF32	"/usr/lib32/libstdbuf.so"
 
-extern char *__progname;
+static int
+appendenv(const char *key, const char *value)
+{
+	char *curval, *newpair;
+	int ret;
+
+	curval = getenv(key);
+	if (curval == NULL)
+		ret = asprintf(&newpair, "%s=%s", key, value);
+	else
+		ret = asprintf(&newpair, "%s=%s:%s", key, curval, value);
+	if (ret > 0)
+		ret = putenv(newpair);
+	if (ret < 0)
+		warn("Failed to set environment variable: %s", key);
+	return (ret);
+}
 
 static void
-usage(int s)
+usage(void)
 {
 
-	fprintf(stderr, "Usage: %s [-e 0|L|B|<sz>] [-i 0|L|B|<sz>] [-o 0|L|B|<sz>] "
-	    "<cmd> [args ...]\n", __progname);
-	exit(s);
+	fprintf(stderr,
+	    "usage: stdbuf [-e 0|L|B|<sz>] [-i 0|L|B|<sz>] [-o 0|L|B|<sz>] "
+	    "<cmd> [args ...]\n");
+	exit(1);
 }
 
 int
 main(int argc, char *argv[])
 {
 	char *ibuf, *obuf, *ebuf;
-	char *preload0, *preload1;
 	int i;
 
 	ibuf = obuf = ebuf = NULL;
@@ -64,9 +80,8 @@ main(int argc, char *argv[])
 		case 'o':
 			obuf = optarg;
 			break;
-		case '?':
 		default:
-			usage(1);
+			usage();
 			break;
 		}
 	}
@@ -85,25 +100,8 @@ main(int argc, char *argv[])
 		warn("Failed to set environment variable: %s=%s",
 		    "_STDBUF_E", ebuf);
 
-	preload0 = getenv("LD_PRELOAD");
-	if (preload0 == NULL)
-		i = asprintf(&preload1, "LD_PRELOAD=" LIBSTDBUF);
-	else
-		i = asprintf(&preload1, "LD_PRELOAD=%s:%s", preload0,
-		    LIBSTDBUF);
-
-	if (i < 0 || putenv(preload1) == -1)
-		warn("Failed to set environment variable: LD_PRELOAD");
-
-	preload0 = getenv("LD_32_PRELOAD");
-	if (preload0 == NULL)
-		i = asprintf(&preload1, "LD_32_PRELOAD=" LIBSTDBUF32);
-	else
-		i = asprintf(&preload1, "LD_32_PRELOAD=%s:%s", preload0,
-		    LIBSTDBUF32);
-
-	if (i < 0 || putenv(preload1) == -1)
-		warn("Failed to set environment variable: LD_32_PRELOAD");
+	appendenv("LD_PRELOAD", LIBSTDBUF);
+	appendenv("LD_32_PRELOAD", LIBSTDBUF32);
 
 	execvp(argv[0], argv);
 	err(2, "%s", argv[0]);