diff --git a/fallocate.1 b/fallocate.1
index ecac614..2fad8d2 100644
--- a/fallocate.1
+++ b/fallocate.1
@@ -1,27 +1,33 @@
-.Dd February 2, 2015
+.Dd September 11, 2015
 .Dt FALLOCATE 1
 .Os ubase
 .Sh NAME
 .Nm fallocate
-.Nd preallocate blocks to a file
+.Nd reallocate files
 .Sh SYNOPSIS
 .Nm
-.Op Fl o Ar offset
-.Fl l Ar length Ar file
+.Op Fl o Ar num
+.Fl l Ar num
+.Ar file ...
 .Sh DESCRIPTION
 .Nm
-preallocates blocks to a file. Only certain filesystems support the
-.Xr fallocate 2
-system call.  This is a very fast operation to allocate uninitialized blocks
-in a file without doing any IO. As of the Linux kernel v2.6.31, the
-.Xr fallocate 2
-system call is supported by the btrfs, ext4, ocfs2, and xfs filesystems.
+if necessary creates and reallocates each
+.Ar file
+resulting in expansion or truncation.
+.sp
+Given the filesystem supports
+.Xr fallocate 2 ,
+it is a very fast method of reallocation.
 .Sh OPTIONS
 .Bl -tag -width Ds
-.It Fl l Ar length
-Specifies the length of the allocation, in bytes.
-.It Fl o
-Specifies the beginning offset of the allocation, in bytes.
+.It Fl l Ar num
+Allocate
+.Ar num
+bytes.
+.It Fl o Ar num
+Offset allocation by
+.Ar num
+bytes.
 .El
 .Sh SEE ALSO
 .Xr fallocate 2
diff --git a/fallocate.c b/fallocate.c
index 8e20cbb..47eb470 100644
--- a/fallocate.c
+++ b/fallocate.c
@@ -2,6 +2,8 @@
 #include <sys/stat.h>
 
 #include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -11,36 +13,43 @@
 static void
 usage(void)
 {
-	eprintf("usage: %s [-o offset] -l length file\n", argv0);
+	eprintf("usage: %s [-o num] -l num file ...\n", argv0);
 }
 
 int
 main(int argc, char *argv[])
 {
-	int fd;
+	int fd, ret = 0;
 	off_t size = 0, offset = 0;
 
 	ARGBEGIN {
 	case 'l':
-		size = estrtol(EARGF(usage()), 10);
+		size = estrtonum(EARGF(usage()), 1, MIN(LLONG_MAX, SIZE_MAX));
 		break;
 	case 'o':
-		offset = estrtol(EARGF(usage()), 10);
+		offset = estrtonum(EARGF(usage()), 0, MIN(LLONG_MAX, SIZE_MAX));
 		break;
 	default:
 		usage();
 	} ARGEND;
 
-	if (argc != 1 || !size)
+	if (!argc || !size)
 		usage();
 
-	fd = open(argv[0], O_RDWR | O_CREAT, 0644);
-	if (fd < 0)
-		eprintf("open %s:", argv[0]);
+	for (; *argv; argc--, argv++) {
+		if ((fd = open(*argv, O_RDWR | O_CREAT, 0644)) < 0) {
+			weprintf("open %s:", *argv);
+			ret = 1;
+		} else if (posix_fallocate(fd, offset, size) < 0) {
+			weprintf("posix_fallocate %s:", *argv);
+			ret = 1;
+		}
 
-	if (posix_fallocate(fd, offset, size) < 0)
-		eprintf("posix_fallocate:");
+		if (fd >= 0 && close(fd) < 0) {
+			weprintf("close %s:", *argv);
+			ret = 1;
+		}
+	}
 
-	close(fd);
-	return 0;
+	return ret;
 }
diff --git a/util.h b/util.h
index 073156d..6ab609e 100644
--- a/util.h
+++ b/util.h
@@ -2,6 +2,14 @@
 #include "arg.h"
 
 #define UTF8_POINT(c) (((c) & 0xc0) != 0x80)
+
+#undef MIN
+#define MIN(x,y)  ((x) < (y) ? (x) : (y))
+#undef MAX
+#define MAX(x,y)  ((x) > (y) ? (x) : (y))
+#undef LIMIT
+#define LIMIT(x, a, b)  (x) = (x) < (a) ? (a) : (x) > (b) ? (b) : (x)
+
 #define LEN(x) (sizeof (x) / sizeof *(x))
 
 /* eprintf.c */