diff --git a/Makefile b/Makefile
index 453607c..71892f7 100644
--- a/Makefile
+++ b/Makefile
@@ -25,6 +25,7 @@ LIBUTILSRC = \
 	libutil/estrtol.c        \
 	libutil/estrtoul.c       \
 	libutil/explicit_bzero.c \
+	libutil/human.c          \
 	libutil/passwd.c         \
 	libutil/proc.c           \
 	libutil/putword.c        \
diff --git a/df.c b/df.c
index 4d595d6..0f0dfea 100644
--- a/df.c
+++ b/df.c
@@ -13,45 +13,6 @@ static int aflag = 0;
 static int hflag = 0;
 static int kflag = 0;
 
-#define CALC_POWER(n, power, base, i) do { \
-	while (n > power) {                \
-		power = power * base;      \
-		i++;                       \
-	}                                  \
-} while(0)
-
-static void
-print_human(
-	const char         *fsname,
-	unsigned long long total,
-	unsigned long long used,
-	unsigned long long avail,
-	int                capacity,
-	const char         *dir)
-{
-	long base = 1024;
-	unsigned long long power_total = base;
-	unsigned long long power_used = base;
-	unsigned long long power_avail = base;
-	char postfixes[] = {'B', 'K', 'M', 'G', 'T', 'P', 'E'};
-	int i = 0, j = 0, k = 0;
-
-	total = total * blksize;
-	used = used * blksize;
-	avail = avail * blksize;
-
-	CALC_POWER(total, power_total, base, i);
-	CALC_POWER(used, power_used, base, j);
-	CALC_POWER(avail, power_avail, base, k);
-
-	total = i ? total / (power_total / base) : total;
-	used = j ? used / (power_used / base) : used;
-	avail = k ? avail / (power_avail / base) : avail;
-	printf("%-12s %9llu%c %9llu%c %9llu%c %7d%%  %s\n",
-	       fsname, total, postfixes[i], used, postfixes[j],
-	       avail, postfixes[k], capacity, dir);
-}
-
 static int
 mnt_show(const char *fsname, const char *dir)
 {
@@ -75,7 +36,8 @@ mnt_show(const char *fsname, const char *dir)
 	}
 
 	if (hflag)
-		print_human(fsname, total, used, avail, capacity, dir);
+		printf("%-12s %9s %9s %9s %7d%% %s\n",
+			fsname, humansize(total*blksize), humansize(used*blksize), humansize(avail*blksize), capacity, dir);
 	else
 		printf("%-12s %9llu %9llu %9llu %7d%%  %s\n",
 		       fsname, total, used, avail, capacity, dir);
diff --git a/libutil/human.c b/libutil/human.c
new file mode 100644
index 0000000..7e39ba5
--- /dev/null
+++ b/libutil/human.c
@@ -0,0 +1,25 @@
+/* See LICENSE file for copyright and license details. */
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+#include "../util.h"
+
+char *
+humansize(off_t n)
+{
+	static char buf[16];
+	const char postfixes[] = "BKMGTPE";
+	double size;
+	int i;
+
+	for (size = n, i = 0; size >= 1024 && i < strlen(postfixes); i++)
+		size /= 1024;
+
+	if (!i)
+		snprintf(buf, sizeof(buf), "%ju", (uintmax_t)n);
+	else
+		snprintf(buf, sizeof(buf), "%.1f%c", size, postfixes[i]);
+
+	return buf;
+}