1 files changed, 9 insertions, 3 deletions

diff --git a/usr.sbin/mountd/mountd.c b/usr.sbin/mountd/mountd.c
index 36b3659ea4871..d119bb9199d6b 100644
--- a/usr.sbin/mountd/mountd.c
+++ b/usr.sbin/mountd/mountd.c
@@ -3434,10 +3434,16 @@ parsecred(char *namelist, struct xucred *cr)
 		/*
 		 * Compress out duplicate.
 		 */
-		cr->cr_ngroups = ngroups - 1;
 		cr->cr_groups[0] = groups[0];
-		for (cnt = 2; cnt < ngroups; cnt++)
-			cr->cr_groups[cnt - 1] = groups[cnt];
+		if (ngroups > 1 && groups[0] == groups[1]) {
+			cr->cr_ngroups = ngroups - 1;
+			for (cnt = 2; cnt < ngroups; cnt++)
+				cr->cr_groups[cnt - 1] = groups[cnt];
+		} else {
+			cr->cr_ngroups = ngroups;
+			for (cnt = 1; cnt < ngroups; cnt++)
+				cr->cr_groups[cnt] = groups[cnt];
+		}
 		return;
 	}
 	/*