diff --git a/tools/tools/build_option_survey/option_survey.sh b/tools/tools/build_option_survey/option_survey.sh
index 46ce167c49d9..c787125c9acd 100644
--- a/tools/tools/build_option_survey/option_survey.sh
+++ b/tools/tools/build_option_survey/option_survey.sh
@@ -117,7 +117,7 @@ trap "umount ${MNT} || true; mdconfig -d -u $MDUNIT" 1 2 15 EXIT
 
 umount $MNT || true
 mdconfig -d -u $MDUNIT || true
-dd if=/dev/zero of=${ODIR}/imgfile bs=1m count=4096
+dd if=/dev/zero of=${ODIR}/imgfile bs=1m count=5120
 mdconfig -a -t vnode -f ${ODIR}/imgfile -u $MDUNIT
 
 # Build & install the reference world