diff --git a/sys/geom/label/g_label.c b/sys/geom/label/g_label.c
index c37ca3511890..13639aedf7b2 100644
--- a/sys/geom/label/g_label.c
+++ b/sys/geom/label/g_label.c
@@ -179,9 +179,25 @@ g_label_mangle_name(char *label, size_t size)
 {
 	struct sbuf *sb;
 	const u_char *c;
+	size_t len, i;
+
+	/* Trim trailing whitespace. */
+	len = strlen(label);
+	for (i = len; i > 0; i--) {
+		if (isspace(label[i - 1]))
+			label[i - 1] = '\0';
+		else
+			break;
+	}
+	if (*label == '\0')
+		return;
+
 
 	sb = sbuf_new(NULL, NULL, size, SBUF_FIXEDLEN);
 	for (c = label; *c != '\0'; c++) {
+		/* Trim leading whitespace. */
+		if (isspace(*c) && sbuf_len(sb) == 0)
+			continue;
 		if (!isprint(*c) || isspace(*c) || *c =='"' || *c == '%')
 			sbuf_printf(sb, "%%%02X", *c);
 		else