diff --git a/tests/zfs-tests/tests/functional/refreserv/refreserv_multi_raidz.ksh b/tests/zfs-tests/tests/functional/refreserv/refreserv_multi_raidz.ksh
index c904a807f1..ff79764bab 100755
--- a/tests/zfs-tests/tests/functional/refreserv/refreserv_multi_raidz.ksh
+++ b/tests/zfs-tests/tests/functional/refreserv/refreserv_multi_raidz.ksh
@@ -61,7 +61,11 @@ poolexists "$TESTPOOL" && log_must_busy zpool destroy "$TESTPOOL"
 # that small test disks may fill before creating small volumes.  However,
 # testing 512b and 1K blocks on ashift=9 pools is an ok approximation for
 # testing the problems that arise from 4K and 8K blocks on ashift=12 pools.
-bps=$(lsblk -nrdo min-io /dev/${alldisks[0]})
+if is_freebsd; then
+	bps=$(diskinfo -v ${alldisks[0]} | awk '/sectorsize/ { print $1 }')
+elif is_linux; then
+	bps=$(lsblk -nrdo min-io /dev/${alldisks[0]})
+fi
 case "$bps" in
 512)
 	allshifts=(9 10 17)
diff --git a/tests/zfs-tests/tests/functional/refreserv/refreserv_raidz.ksh b/tests/zfs-tests/tests/functional/refreserv/refreserv_raidz.ksh
index 9f25242de6..22891ef1d5 100755
--- a/tests/zfs-tests/tests/functional/refreserv/refreserv_raidz.ksh
+++ b/tests/zfs-tests/tests/functional/refreserv/refreserv_raidz.ksh
@@ -63,7 +63,11 @@ poolexists "$TESTPOOL" && log_must_busy zpool destroy "$TESTPOOL"
 # that small test disks may fill before creating small volumes.  However,
 # testing 512b and 1K blocks on ashift=9 pools is an ok approximation for
 # testing the problems that arise from 4K and 8K blocks on ashift=12 pools.
-bps=$(lsblk -nrdo min-io /dev/${alldisks[0]})
+if is_freebsd; then
+	bps=$(diskinfo -v ${alldisks[0]} | awk '/sectorsize/ { print $1 }')
+elif is_linux; then
+	bps=$(lsblk -nrdo min-io /dev/${alldisks[0]})
+fi
 log_must test "$bps" -eq 512 -o "$bps" -eq 4096
 case "$bps" in
 512)