diff --git a/pishrink.sh b/pishrink.sh
index 19ec060..11f4771 100755
--- a/pishrink.sh
+++ b/pishrink.sh
@@ -29,7 +29,7 @@ if (( EUID != 0 )); then
 fi
 
 #Check that what we need is installed
-A=`which parted 2>&1`
+A=$(which parted 2>&1)
 if (( $? != 0 )); then
   echo "ERROR: parted is not installed."
   exit -4
@@ -47,20 +47,20 @@ if [ -n "$2" ]; then
 fi
 
 #Gather info
-beforesize=`ls -lah "$img" | cut -d ' ' -f 5`
-partnum=`parted -m "$img" unit B print | tail -n 1 | cut -d ':' -f 1 | tr -d '\n'`
-partstart=`parted -m "$img" unit B print | tail -n 1 | cut -d ':' -f 2 | tr -d 'B\n'`
-loopback=`losetup -f --show -o $partstart "$img"`
-currentsize=`tune2fs -l $loopback | grep 'Block count' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n'`
-blocksize=`tune2fs -l $loopback | grep 'Block size' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n'`
+beforesize=$(ls -lah "$img" | cut -d ' ' -f 5)
+partnum=$(parted -m "$img" unit B print | tail -n 1 | cut -d ':' -f 1 | tr -d '\n')
+partstart=$(parted -m "$img" unit B print | tail -n 1 | cut -d ':' -f 2 | tr -d 'B\n')
+loopback=$(losetup -f --show -o $partstart "$img")
+currentsize=$(tune2fs -l $loopback | grep 'Block count' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n')
+blocksize=$(tune2fs -l $loopback | grep 'Block size' | tr -d ' ' | cut -d ':' -f 2 | tr -d '\n')
 
 #Check if we should make pi expand rootfs on next boot
 if [ "$should_skip_autoexpand" = false ]; then
   #Make pi expand rootfs on next boot
-  mountdir=`mktemp -d`
+  mountdir=$(mktemp -d)
   mount $loopback $mountdir
 
-  if [ `md5sum $mountdir/etc/rc.local | cut -d ' ' -f 1` != "0542054e9ff2d2e0507ea1ffe7d4fc87" ]; then
+  if [ $(md5sum $mountdir/etc/rc.local | cut -d ' ' -f 1) != "0542054e9ff2d2e0507ea1ffe7d4fc87" ]; then
     echo Creating new /etc/rc.local
     mv $mountdir/etc/rc.local $mountdir/etc/rc.local.bak
     #####Do not touch the following lines#####
@@ -132,19 +132,19 @@ fi
 
 #Make sure filesystem is ok
 e2fsck -p -f $loopback
-minsize=`resize2fs -P $loopback | cut -d ':' -f 2 | tr -d ' ' | tr -d '\n'`
+minsize=$(resize2fs -P $loopback | cut -d ':' -f 2 | tr -d ' ' | tr -d '\n')
 if [[ $currentsize -eq $minsize ]]; then
   echo ERROR: Image already shrunk to smallest size
   exit -6
 fi
 
 #Add some free space to the end of the filesystem
-if [[ `expr $currentsize - $minsize - 5000` -gt 0 ]]; then
-  minsize=`expr $minsize + 5000 | tr -d '\n'`
-elif [[ `expr $currentsize - $minsize - 1000` -gt 0 ]]; then
-  minsize=`expr $minsize + 1000 | tr -d '\n'`
-elif [[ `expr $currentsize - $minsize - 100` -gt 0 ]]; then
-  minsize=`expr $minsize + 100 | tr -d '\n'`
+if [[ $(expr $currentsize - $minsize - 5000) -gt 0 ]]; then
+  minsize=$(expr $minsize + 5000 | tr -d '\n')
+elif [[ $(expr $currentsize - $minsize - 1000) -gt 0 ]]; then
+  minsize=$(expr $minsize + 1000 | tr -d '\n')
+elif [[ $(expr $currentsize - $minsize - 100) -gt 0 ]]; then
+  minsize=$(expr $minsize + 100 | tr -d '\n')
 fi
 
 #Shrink filesystem
@@ -161,14 +161,14 @@ sleep 1
 
 #Shrink partition
 losetup -d $loopback
-partnewsize=`expr $minsize \* $blocksize | tr -d '\n'`
-newpartend=`expr $partstart + $partnewsize | tr -d '\n'`
-part1=`parted "$img" rm $partnum`
-part2=`parted "$img" unit B mkpart primary $partstart $newpartend`
+partnewsize=$(expr $minsize \* $blocksize | tr -d '\n')
+newpartend=$(expr $partstart + $partnewsize | tr -d '\n')
+part1=$(parted "$img" rm $partnum)
+part2=$(parted "$img" unit B mkpart primary $partstart $newpartend)
 
 #Truncate the file
-endresult=`parted -m "$img" unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B\n'`
+endresult=$(parted -m "$img" unit B print free | tail -1 | cut -d ':' -f 2 | tr -d 'B\n')
 truncate -s $endresult "$img"
-aftersize=`ls -lah "$img" | cut -d ' ' -f 5`
+aftersize=$(ls -lah "$img" | cut -d ' ' -f 5)
 
 echo "Shrunk $img from $beforesize to $aftersize"