diff --git a/lib/functions/host/prepare-host.sh b/lib/functions/host/prepare-host.sh
index 022132caa9..1bde380f28 100644
--- a/lib/functions/host/prepare-host.sh
+++ b/lib/functions/host/prepare-host.sh
@@ -260,7 +260,7 @@ prepare_host() {
 
 	# check free space (basic)
 	local freespace=$(findmnt --target "${SRC}" -n -o AVAIL -b 2> /dev/null) # in bytes
-	if [[ -n $freespace && $(($freespace / 1073741824)) -lt 10 ]]; then
+	if [ -n "$freespace" ] && [ "$((freespace / 1073741824))" -lt 10 ]; then
 		display_alert "Low free space left" "$(($freespace / 1073741824)) GiB" "wrn"
 		# pause here since dialog-based menu will hide this message otherwise
 		echo -e "Press \e[0;33m<Ctrl-C>\x1B[0m to abort compilation, \e[0;33m<Enter>\x1B[0m to ignore and continue"