diff --git a/lib/libutil/libutil.h b/lib/libutil/libutil.h
index 2190a532f793..b5ff6fd9e078 100644
--- a/lib/libutil/libutil.h
+++ b/lib/libutil/libutil.h
@@ -146,6 +146,7 @@ struct fstab;
 struct quotafile *quota_open(struct fstab *, int, int);
 const char *quota_fsname(const struct quotafile *);
 const char *quota_qfname(const struct quotafile *);
+int quota_maxid(struct quotafile *);
 int quota_check_path(const struct quotafile *, const char *path);
 int quota_read(struct quotafile *, struct dqblk *, int);
 int quota_write_limits(struct quotafile *, struct dqblk *, int);
diff --git a/lib/libutil/quotafile.3 b/lib/libutil/quotafile.3
index 4762bf92558c..d0c27d730b89 100644
--- a/lib/libutil/quotafile.3
+++ b/lib/libutil/quotafile.3
@@ -32,6 +32,7 @@
 .Nm quota_open
 .Nm quota_fsname
 .Nm quota_qfname
+.Nm quota_maxid
 .Nm quota_check_path
 .Nm quota_read
 .Nm quota_write_limits
@@ -44,8 +45,9 @@
 .In sys/param.h
 .In sys/mount.h
 .In ufs/ufs/quota.h
-.In libutil.h
+.In fcntl.h
 .In fstab.h
+.In libutil.h
 .Ft "struct quotafile *"
 .Fn quota_open "struct fstab *fs" "int quotatype" "int openflags"
 .Ft "const char *"
@@ -53,6 +55,8 @@
 .Ft "const char *"
 .Fn quota_qfname "const struct quotafile *qf"
 .Ft int
+.Fn quota_maxid "const struct quotafile *qf"
+.Ft int
 .Fn quota_check_path "const struct quotafile *qf" "const char *path"
 .Ft int
 .Fn quota_read "struct quotafile *qf" "struct dqblk *dqb" "int id"
@@ -116,6 +120,14 @@ argument.
 Note that this may be a symbolic link to the actual file.
 .Pp
 The
+.Fn quota_maxid
+function returns the maximum user (or group)
+.Va id
+contained in the quota file associated with its
+.Va qf
+argument.
+.Pp
+The
 .Fn quota_check_path
 function checks if the specified path is within the filesystem that
 corresponds to its
diff --git a/lib/libutil/quotafile.c b/lib/libutil/quotafile.c
index 6dcb6979fb12..4c63a17b7784 100644
--- a/lib/libutil/quotafile.c
+++ b/lib/libutil/quotafile.c
@@ -128,13 +128,13 @@ quota_open(struct fstab *fs, int quotatype, int openflags)
 	if (stat(qf->fsname, &st) != 0)
 		goto error;
 	qf->dev = st.st_dev;
+	serrno = hasquota(fs, quotatype, qf->qfname, sizeof(qf->qfname));
 	qcmd = QCMD(Q_GETQUOTA, quotatype);
 	if (quotactl(fs->fs_file, qcmd, 0, &dqh) == 0) {
 		qf->wordsize = 64;
-		qf->fd = -1;
 		return (qf);
 	}
-	if (!hasquota(fs, quotatype, qf->qfname, sizeof(qf->qfname))) {
+	if (serrno == 0) {
 		errno = EOPNOTSUPP;
 		goto error;
 	}
@@ -231,6 +231,24 @@ quota_check_path(const struct quotafile *qf, const char *path)
 	return (st.st_dev == qf->dev);
 }
 
+int
+quota_maxid(struct quotafile *qf)
+{
+	struct stat st;
+
+	if (stat(qf->qfname, &st) < 0)
+		return (0);
+	switch (qf->wordsize) {
+	case 32:
+		return (st.st_size / sizeof(struct dqblk32));
+	case 64:
+		return (st.st_size / sizeof(struct dqblk64) - 1);
+	default:
+		return (0);
+	}
+	/* not reached */
+}
+
 static int
 quota_read32(struct quotafile *qf, struct dqblk *dqb, int id)
 {
@@ -242,7 +260,7 @@ quota_read32(struct quotafile *qf, struct dqblk *dqb, int id)
 		return (-1);
 	switch (read(qf->fd, &dqb32, sizeof(dqb32))) {
 	case 0:
-		memset(&dqb, 0, sizeof(*dqb));
+		memset(dqb, 0, sizeof(*dqb));
 		return (0);
 	case sizeof(dqb32):
 		dqb->dqb_bhardlimit = dqb32.dqb_bhardlimit;
@@ -270,7 +288,7 @@ quota_read64(struct quotafile *qf, struct dqblk *dqb, int id)
 		return (-1);
 	switch (read(qf->fd, &dqb64, sizeof(dqb64))) {
 	case 0:
-		memset(&dqb, 0, sizeof(*dqb));
+		memset(dqb, 0, sizeof(*dqb));
 		return (0);
 	case sizeof(dqb64):
 		dqb->dqb_bhardlimit = be64toh(dqb64.dqb_bhardlimit);