diff --git a/usr.sbin/mfiutil/mfi_bbu.c b/usr.sbin/mfiutil/mfi_bbu.c
--- a/usr.sbin/mfiutil/mfi_bbu.c
+++ b/usr.sbin/mfiutil/mfi_bbu.c
@@ -40,41 +40,23 @@
 
 /* The autolearn period is given in seconds. */
 void
-mfi_autolearn_period(uint32_t period, char *buf, size_t sz)
+mfi_autolearn_period(FILE *fp, uint32_t period)
 {
 	unsigned int d, h;
-	char *tmp;
 
 	d = period / (24 * 3600);
 	h = (period % (24 * 3600)) / 3600;
 
-	tmp = buf;
 	if (d != 0) {
-		int fmt_len;
-		fmt_len = snprintf(buf, sz, "%u day%s", d, d == 1 ? "" : "s");
-		if (fmt_len < 0) {
-			*buf = 0;
-			return;
-		}
-		if ((size_t)fmt_len >= sz) {
-			return;
-		}
-		tmp += fmt_len;
-		sz -= tmp - buf;
-		if (h != 0) {
-			fmt_len = snprintf(tmp, sz, ", ");
-			if (fmt_len < 0 || (size_t)fmt_len >= sz) {
-				return;
-			}
-			tmp += fmt_len;
-			sz -= 2;
-		}
+		fprintf(fp, "%u day%s", d, d == 1 ? "" : "s");
+		if (h != 0)
+			fprintf(fp, ", ");
 	}
 	if (h != 0)
-		snprintf(tmp, sz, "%u hour%s", h, h == 1 ? "" : "s");
+		fprintf(fp, "%u hour%s", h, h == 1 ? "" : "s");
 
 	if (d == 0 && h == 0)
-		snprintf(tmp, sz, "less than 1 hour");
+		fprintf(fp, "less than 1 hour");
 }
 
 /* The time to the next relearn is given in seconds since 1/1/2000. */
@@ -96,21 +78,21 @@
 }
 
 void
-mfi_autolearn_mode(uint8_t mode, char *buf, size_t sz)
+mfi_autolearn_mode(FILE *fp, uint8_t mode)
 {
 
 	switch (mode) {
 	case 0:
-		snprintf(buf, sz, "enabled");
+		fprintf(fp, "enabled");
 		break;
 	case 1:
-		snprintf(buf, sz, "disabled");
+		fprintf(fp, "disabled");
 		break;
 	case 2:
-		snprintf(buf, sz, "warn via event");
+		fprintf(fp, "warn via event");
 		break;
 	default:
-		snprintf(buf, sz, "mode 0x%02x", mode);
+		fprintf(fp, "mode 0x%02x", mode);
 		break;
 	}
 }
diff --git a/usr.sbin/mfiutil/mfi_show.c b/usr.sbin/mfiutil/mfi_show.c
--- a/usr.sbin/mfiutil/mfi_show.c
+++ b/usr.sbin/mfiutil/mfi_show.c
@@ -218,8 +218,9 @@
 	printf("      Current Voltage: %d mV\n", stat.voltage);
 	printf("          Temperature: %d C\n", stat.temperature);
 	if (show_props) {
-		mfi_autolearn_period(props.auto_learn_period, buf, sizeof(buf));
-		printf("     Autolearn period: %s\n", buf);
+		printf("     Autolearn period: ");
+		mfi_autolearn_period(stdout, props.auto_learn_period);
+		printf("\n");
 		if (props.auto_learn_mode != 0)
 			snprintf(buf, sizeof(buf), "never");
 		else
@@ -229,8 +230,9 @@
 		printf(" Learn delay interval: %u hour%s\n",
 		    props.learn_delay_interval,
 		    props.learn_delay_interval != 1 ? "s" : "");
-		mfi_autolearn_mode(props.auto_learn_mode, buf, sizeof(buf));
-		printf("       Autolearn mode: %s\n", buf);
+		printf("       Autolearn mode: ");
+		mfi_autolearn_mode(stdout, props.auto_learn_mode);
+		printf("\n");
 		if (props.bbu_mode != 0)
 			printf("             BBU Mode: %d\n", props.bbu_mode);
 	}
diff --git a/usr.sbin/mfiutil/mfiutil.h b/usr.sbin/mfiutil/mfiutil.h
--- a/usr.sbin/mfiutil/mfiutil.h
+++ b/usr.sbin/mfiutil/mfiutil.h
@@ -175,9 +175,9 @@
 	    uint8_t *statusp);
 int	mfi_bbu_set_props(int fd, struct mfi_bbu_properties *props,
 	    uint8_t *statusp);
-void	mfi_autolearn_period(uint32_t, char *, size_t);
+void	mfi_autolearn_period(FILE *, uint32_t);
 void	mfi_next_learn_time(uint32_t, char *, size_t);
-void	mfi_autolearn_mode(uint8_t, char *, size_t);
+void	mfi_autolearn_mode(FILE *, uint8_t);
 int	get_mfi_unit(const char *dev);
 char	*get_mfi_type(const char *dev);