diff --git a/build.sh b/build.sh
index 661fbd8..2a11a8c 100644
--- a/build.sh
+++ b/build.sh
@@ -1,5 +1,6 @@
+#!/usr/bin/env bash
 set -e
 
 docker build --tag dsm .
 docker images dsm:latest --format "{{.Repository}}:{{.Tag}} -> {{.Size}}"
-docker run --rm -it --name dsm --device=/dev/kvm:/dev/kvm --device=/dev/net/tun:/dev/net/tun --cap-add NET_ADMIN -p 80:5000 -p 443:5001 -p 5000:5000 -p 5001:5001 -v ${PWD}/img:/storage docker.io/library/dsm
+docker run --rm -it --name dsm --device="/dev/kvm:/dev/kvm" --device="/dev/net/tun:/dev/net/tun" --cap-add NET_ADMIN -p 80:5000 -p 443:5001 -p 5000:5000 -p 5001:5001 -v "${PWD}/img:/storage" docker.io/library/dsm
diff --git a/install.sh b/install.sh
index b1c46f1..c7b1abc 100644
--- a/install.sh
+++ b/install.sh
@@ -70,7 +70,7 @@ NUMBLOCKS="622560" # 2550005760 / 4096
 MOUNT="/mnt/tmp"
 rm -rf $MOUNT && mkdir -p $MOUNT
 
-[ mount -t ext4 -o loop,offset=$OFFSET $SYSTEM $MOUNT 2>/dev/null ] && PRIVILEGED=true
+mount -t ext4 -o loop,offset=$OFFSET $SYSTEM $MOUNT 2>/dev/null && PRIVILEGED=true
 
 rm -rf $MOUNT/{,.[!.],..?}*
 
@@ -88,7 +88,7 @@ if [ "$PRIVILEGED" = false ]; then
 
 else
 
- umount $MOUNT
+  umount $MOUNT
 
 fi
 
diff --git a/qemu-ifdown b/qemu-ifdown
index 2ffdfa7..58a5388 100755
--- a/qemu-ifdown
+++ b/qemu-ifdown
@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-QEMU_BRIDGE='qemubr0'
+#QEMU_BRIDGE='qemubr0'
 
 ip link set dev $1 nomaster
 ip link set dev $1 down
diff --git a/run.sh b/run.sh
index 3fd13cc..5f4382d 100755
--- a/run.sh
+++ b/run.sh
@@ -49,7 +49,7 @@ function default_intf() {
 # on our current address/routes. We "steal" the container's IP, and lease
 # it to the VM once it starts up.
 /run/generate-dhcpd-conf $QEMU_BRIDGE > $DHCPD_CONF_FILE
-default_dev=`default_intf`
+default_dev=$(default_intf)
 
 # Now we start modifying the networking configuration. First we clear out
 # the IP address of the default device (will also have the side-effect of
@@ -113,7 +113,7 @@ _graceful_shutdown() {
   echo 'system_powerdown' | nc -q 1 localhost ${QEMU_MONPORT}>/dev/null 2>&1
   echo ""
   while echo 'info version'|nc -q 1 localhost ${QEMU_MONPORT:-7100}>/dev/null 2>&1 && [ "${COUNT}" -lt "${QEMU_POWERDOWN_TIMEOUT}" ]; do
-    let COUNT++
+    (( COUNT++ )) || true
     echo "QEMU still running. Retrying... (${COUNT}/${QEMU_POWERDOWN_TIMEOUT})"
     sleep 1
   done
diff --git a/serial.sh b/serial.sh
index b275c44..1dbaef4 100644
--- a/serial.sh
+++ b/serial.sh
@@ -2,6 +2,6 @@
 
 permanent="DSM"
 serialstart="2000"
-serialnum="$(echo "$serialstart" | tr ' ' '\n' | sort -R | tail -1)$permanent"$(printf "%06d" $(($RANDOM % 30000 + 1)))
+serialnum="$(echo "$serialstart" | tr ' ' '\n' | sort -R | tail -1)$permanent"$(printf "%06d" $((RANDOM % 30000 + 1)))
 
 echo $serialnum