diff --git a/contrib/mtree/mtree.h b/contrib/mtree/mtree.h
--- a/contrib/mtree/mtree.h
+++ b/contrib/mtree/mtree.h
@@ -46,7 +46,9 @@
 	struct timespec	st_mtimespec;		/* last modification time */
 	char	*slink;				/* symbolic link reference */
 	uid_t	st_uid;				/* uid */
+	char	*uname;
 	gid_t	st_gid;				/* gid */
+	char	*gname;
 #define	MBITS	(S_ISUID|S_ISGID|S_ISTXT|S_IRWXU|S_IRWXG|S_IRWXO)
 	mode_t	st_mode;			/* mode */
 	dev_t	st_rdev;			/* device type */
diff --git a/contrib/mtree/spec.c b/contrib/mtree/spec.c
--- a/contrib/mtree/spec.c
+++ b/contrib/mtree/spec.c
@@ -342,7 +342,8 @@
 			    nodetype(cur->type));
 		if (MATCHFLAG(F_UID | F_UNAME)) {
 			if (keys & F_UNAME &&
-			    (name = user_from_uid(cur->st_uid, 1)) != NULL)
+			    (name = cur->uname ? cur->uname :
+			      user_from_uid(cur->st_uid, 1)) != NULL)
 				appendfield(fp, pathlast, "uname=%s", name);
 			else
 				appendfield(fp, pathlast, "uid=%u",
@@ -350,7 +351,8 @@
 		}
 		if (MATCHFLAG(F_GID | F_GNAME)) {
 			if (keys & F_GNAME &&
-			    (name = group_from_gid(cur->st_gid, 1)) != NULL)
+			    (name = cur->gname ? cur->gname :
+			      group_from_gid(cur->st_gid, 1)) != NULL)
 				appendfield(fp, pathlast, "gname=%s", name);
 			else
 				appendfield(fp, pathlast, "gid=%u",
@@ -582,9 +584,12 @@
 		case F_GNAME:
 			if (mtree_Wflag)	/* don't parse if whacking */
 				break;
-			if (gid_from_group(val, &gid) == -1)
-				mtree_err("unknown group `%s'", val);
-			ip->st_gid = gid;
+			if (gid_from_group(val, &gid) == -1) {
+				// mtree_err("unknown group `%s'", val);
+				ip->uname = strdup(val);
+			} else {
+				ip->st_gid = gid;
+			}
 			break;
 		case F_MD5:
 			if (val[0]=='0' && val[1]=='x')
@@ -660,9 +665,12 @@
 		case F_UNAME:
 			if (mtree_Wflag)	/* don't parse if whacking */
 				break;
-			if (uid_from_user(val, &uid) == -1)
-				mtree_err("unknown user `%s'", val);
-			ip->st_uid = uid;
+			if (uid_from_user(val, &uid) == -1) {
+				//mtree_err("unknown user `%s'", val);
+				ip->uname = strdup(val);
+			} else {
+				ip->st_uid = uid;
+			}
 			break;
 		case F_SHA256:
 			if (val[0]=='0' && val[1]=='x')
diff --git a/contrib/mtree/specspec.c b/contrib/mtree/specspec.c
--- a/contrib/mtree/specspec.c
+++ b/contrib/mtree/specspec.c
@@ -64,11 +64,15 @@
 	if (f & F_GID)
 		printf(" gid=%d", n->st_gid);
 	if (f & F_GNAME) {
-		gr = getgrgid(n->st_gid);
-		if (gr == NULL)
-			printf(" gid=%d", n->st_gid);
-		else
-			printf(" gname=%s", gr->gr_name);
+		if (n->gname != NULL) {
+			printf(" gname=%s", n->gname); 
+		} else {
+			gr = getgrgid(n->st_gid);
+			if (gr == NULL)
+				printf(" gid=%d", n->st_gid);
+			else
+				printf(" gname=%s", gr->gr_name);
+		}
 	}
 	if (f & F_MODE)
 		printf(" mode=%o", n->st_mode);
@@ -79,11 +83,15 @@
 	if (f & F_UID)
 		printf(" uid=%d", n->st_uid);
 	if (f & F_UNAME) {
-		pw = getpwuid(n->st_uid);
-		if (pw == NULL)
-			printf(" uid=%d", n->st_uid);
-		else
-			printf(" uname=%s", pw->pw_name);
+		if (n->uname != NULL) {
+			printf(" uname=%s", n->uname);
+		} else {
+			pw = getpwuid(n->st_uid);
+			if (pw == NULL)
+				printf(" uid=%d", n->st_uid);
+			else
+				printf(" uname=%s", pw->pw_name);
+		}
 	}
 	if (f & F_MD5)
 		printf(" %s=%s", MD5KEY, n->md5digest);