diff --git a/README b/README
index 12ffd9c..8bb82fe 100644
--- a/README
+++ b/README
@@ -60,7 +60,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
 =* setsid          non-posix                       none
 =* sleep           yes                             none
    sort            no                              -m, -o, -d, -f, -i
-   split           yes                             none
+=* split           yes                             none
 =  sponge          non-posix                       none
    strings         no                              -a, -n, -t
 =  sync            non-posix                       none
diff --git a/split.c b/split.c
index 6151ef4..b14d7e3 100644
--- a/split.c
+++ b/split.c
@@ -8,107 +8,8 @@
 
 #include "util.h"
 
-static int itostr(char *, int, int);
-static FILE *nextfile(FILE *, char *, int, int);
-
-static void
-usage(void)
-{
-	eprintf("usage: split [-d] [-a len] [-b [bytes[k|m|g]]] [-l [lines]] [input [prefix]]\n");
-}
-
 static int base = 26, start = 'a';
 
-int
-main(int argc, char *argv[])
-{
-	int plen, slen = 2;
-	int ch;
-	char name[NAME_MAX+1];
-	char *prefix = "x";
-	char *file = NULL;
-	char *tmp, *end;
-	size_t size = 1000, scale = 1, n;
-	int always = 0;
-	FILE *in = stdin, *out = NULL;
-
-	ARGBEGIN {
-	case 'b':
-		always = 1;
-		tmp = ARGF();
-		if (!tmp)
-			break;
-
-		size = strtoull(tmp, &end, 10);
-		if (!*end)
-			break;
-		switch (toupper((int)*end)) {
-		case 'K':
-			scale = 1024;
-			break;
-		case 'M':
-			scale = 1024L * 1024L;
-			break;
-		case 'G':
-			scale = 1024L * 1024L * 1024L;
-			break;
-		default:
-			usage();
-		}
-		if (size > (SIZE_MAX/scale))
-			eprintf("'%s': out of range\n", tmp);
-		size *= scale;
-		break;
-	case 'l':
-		always = 0;
-		tmp = ARGF();
-		if (tmp)
-			size = estrtonum(tmp, 0, MIN(LLONG_MAX, SIZE_MAX));
-		break;
-	case 'a':
-		slen = estrtonum(EARGF(usage()), 0, INT_MAX);
-		break;
-	case 'd':
-		base = 10;
-		start = '0';
-		break;
-	default:
-		usage();
-	} ARGEND;
-
-	if (*argv)
-		file = *argv++;
-	if (*argv)
-		prefix = *argv++;
-	if (*argv)
-		usage();
-
-	plen = strlen(prefix);
-	if (plen+slen > NAME_MAX)
-		eprintf("names cannot exceed %d bytes\n", NAME_MAX);
-	strlcpy(name, prefix, sizeof(name));
-
-	if (file && strcmp(file, "-") != 0) {
-		in = fopen(file, "r");
-		if (!in)
-			eprintf("'%s':", file);
-	}
-
-Nextfile:
-	while ((out = nextfile(out, name, plen, slen))) {
-		n = 0;
-		while ((ch = getc(in)) != EOF) {
-			putc(ch, out);
-			n += (always || ch == '\n');
-			if (n >= size)
-				goto Nextfile;
-		}
-		fclose(out);
-		break;
-	}
-	return 0;
-}
-
 int
 itostr(char *str, int x, int n)
 {
@@ -125,17 +26,110 @@ itostr(char *str, int x, int n)
 FILE *
 nextfile(FILE *f, char *buf, int plen, int slen)
 {
-	static int n = 0;
-	int s;
+	static int filecount = 0;
 
 	if (f)
 		fclose(f);
-	s = itostr(buf+plen, n++, slen);
-	if (s < 0)
+	if (itostr(buf + plen, filecount++, slen) < 0)
 		return NULL;
 
-	f = fopen(buf, "w");
-	if (!f)
+	if (!(f = fopen(buf, "w")))
 		eprintf("'%s':", buf);
 	return f;
 }
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-a len] [-b bytes[k|m|g]] [-d] [-l lines] "
+	        "[input [prefix]]\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	FILE *in = stdin, *out = NULL;
+	char name[NAME_MAX + 1];
+	char *prefix = "x";
+	char *file = NULL;
+	char *tmp, *end;
+	size_t size = 1000, scale = 1, n;
+	int ch, plen, slen = 2, always = 0;
+	long l;
+
+	ARGBEGIN {
+	case 'a':
+		slen = estrtonum(EARGF(usage()), 0, INT_MAX);
+		break;
+	case 'b':
+		always = 1;
+		tmp = EARGF(usage());
+		l = strtol(tmp, &end, 10);
+		if (l <= 0)
+			eprintf("invalid number of bytes: %s\n", tmp);
+		size = (size_t)l;
+		if (!*end)
+			break;
+		switch (toupper((int)*end)) {
+		case 'K':
+			scale = 1024;
+			break;
+		case 'M':
+			scale = 1024L * 1024L;
+			break;
+		case 'G':
+			scale = 1024L * 1024L * 1024L;
+			break;
+		default:
+			usage();
+		}
+		if (size > (SIZE_MAX / scale))
+			eprintf("'%s': out of range\n", tmp);
+		size *= scale;
+		break;
+	case 'd':
+		base = 10;
+		start = '0';
+		break;
+	case 'l':
+		always = 0;
+		tmp = EARGF(usage());
+		size = estrtonum(tmp, 1, MIN(LLONG_MAX, SIZE_MAX));
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (*argv)
+		file = *argv++;
+	if (*argv)
+		prefix = *argv++;
+	if (*argv)
+		usage();
+
+	plen = strlen(prefix);
+	if (plen + slen > NAME_MAX)
+		eprintf("names cannot exceed %d bytes\n", NAME_MAX);
+	strlcpy(name, prefix, sizeof(name));
+
+	if (file && strcmp(file, "-") != 0) {
+		if (!(in = fopen(file, "r")))
+			eprintf("'%s':", file);
+	}
+
+	n = 0;
+	while ((ch = getc(in)) != EOF) {
+		if (!out || n >= size) {
+			if (!(out = nextfile(out, name, plen, slen)))
+				eprintf("fopen: %s:", name);
+			n = 0;
+		}
+		n += (always || ch == '\n');
+		putc(ch, out);
+	}
+	if (in != stdin)
+		fclose(in);
+	if (out)
+		fclose(out);
+	return 0;
+}