diff --git a/bootstrap.d/13-kernel.sh b/bootstrap.d/13-kernel.sh
index e86ae33..a662049 100644
--- a/bootstrap.d/13-kernel.sh
+++ b/bootstrap.d/13-kernel.sh
@@ -108,7 +108,7 @@ if [ "$BUILD_KERNEL" = true ] ; then
             echo "CONFIG_CRYPTO_XTS=y"
             echo "CONFIG_CRYPTO_SHA512=y"
             echo "CONFIG_CRYPTO_MANAGER=y"
-          } >> ${KERNEL_DIR}/.config
+          } >> "${KERNEL_DIR}"/.config
         fi
       fi
 
@@ -139,7 +139,7 @@ if [ "$BUILD_KERNEL" = true ] ; then
     make -C "${KERNEL_DIR}" -j"${KERNEL_THREADS}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" CC="${cc}" "${KERNEL_BIN_IMAGE}" dtbs
 
     # Cross compile kernel modules
-    if [ "$(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config")" ] ; then
+    if grep -q "CONFIG_MODULES=y" "${KERNEL_DIR}/.config" ; then
       make -C "${KERNEL_DIR}" -j"${KERNEL_THREADS}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" CC="${cc}" modules
     fi
   fi
@@ -153,16 +153,16 @@ if [ "$BUILD_KERNEL" = true ] ; then
 
   # Install kernel modules
   if [ "$ENABLE_REDUCE" = true ] ; then
-    if [ "$(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config")" ] ; then
+    if grep -q "CONFIG_MODULES=y" "${KERNEL_DIR}/.config" ; then
       make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=../../.. modules_install
     fi
   else
-    if [ "$(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config")" ] ; then
+    if grep -q "CONFIG_MODULES=y" "${KERNEL_DIR}/.config" ; then
       make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_PATH=../../.. modules_install
     fi
 
     # Install kernel firmware
-    if [ "$(grep "^firmware_install:" "${KERNEL_DIR}/Makefile")" ] ; then
+    if grep -q "^firmware_install:" "${KERNEL_DIR}/Makefile" ; then
       make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_FW_PATH=../../../lib firmware_install
     fi
   fi
@@ -225,8 +225,8 @@ if [ "$BUILD_KERNEL" = true ] ; then
     rm -fr "${KERNEL_DIR}"
   else
     # Prepare compiled kernel modules
-    if [ "$(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config")" ] ; then
-      if [ "$(grep "^modules_prepare:" "${KERNEL_DIR}/Makefile")" ] ; then
+    if grep -q "CONFIG_MODULES=y" "${KERNEL_DIR}/.config" ; then
+      if grep -q "^modules_prepare:" "${KERNEL_DIR}/Makefile" ; then
         make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" modules_prepare
       fi
 
diff --git a/bootstrap.d/15-rpi-config.sh b/bootstrap.d/15-rpi-config.sh
index de86adf..91e16e1 100644
--- a/bootstrap.d/15-rpi-config.sh
+++ b/bootstrap.d/15-rpi-config.sh
@@ -104,6 +104,12 @@ if [ "$RPI_MODEL" = 3 ] || [ "$RPI_MODEL" = 3P ] ; then
     # Copy downloaded sources
     mv "${temp_dir}/pi-bluetooth" "${R}/tmp/"
 
+    # Raspberry-sys-mod package for /dev/serial device needed by bluetooth service
+    as_nobody wget -q -O "${R}/tmp/pi-bluetooth/99-com.rules" https://raw.githubusercontent.com/RPi-Distro/raspberrypi-sys-mods/master/etc.armhf/udev/rules.d/99-com.rules	
+    # Bluetooth firmware from arch aur https://aur.archlinux.org/packages/pi-bluetooth/
+    as_nobody wget -q -O "${R}/tmp/pi-bluetooth/LICENCE.broadcom_bcm43xx" https://aur.archlinux.org/cgit/aur.git/plain/LICENCE.broadcom_bcm43xx?h=pi-bluetooth
+    as_nobody wget -q -O "${R}/tmp/pi-bluetooth/BCM43430A1.hcd" https://aur.archlinux.org/cgit/aur.git/plain/BCM43430A1.hcd?h=pi-bluetooth
+
     # Set permissions
     chown -R root:root "${R}/tmp/pi-bluetooth"
 
@@ -116,12 +122,15 @@ if [ "$RPI_MODEL" = 3 ] || [ "$RPI_MODEL" = 3P ] ; then
 
     # Install Firmware Flash file and apropiate licence
     mkdir "${ETC_DIR}/firmware/"
-
-    wget -O "${R}/tmp/pi-bluetooth/LICENCE.broadcom_bcm43xx" https://aur.archlinux.org/cgit/aur.git/plain/LICENCE.broadcom_bcm43xx?h=pi-bluetooth
-    wget -O "${R}/tmp/pi-bluetooth/BCM43430A1.hcd" https://aur.archlinux.org/cgit/aur.git/plain/BCM43430A1.hcd?h=pi-bluetooth
-    
-    # Get /dev/serial back for compability
-    wget -O "${ETC_DIR}/udev/rules.d/99-com.rules" https://raw.githubusercontent.com/RPi-Distro/raspberrypi-sys-mods/master/etc.armhf/udev/rules.d/99-com.rules
+    install_readonly "${R}/tmp/pi-bluetooth/LICENCE.broadcom_bcm43xx" "${ETC_DIR}/firmware/LICENCE.broadcom_bcm43xx"
+    install_readonly "${R}/tmp/pi-bluetooth/BCM43430A1.hcd" "${ETC_DIR}/firmware/LICENCE.broadcom_bcm43xx"
+    install_readonly "${R}/tmp/pi-bluetooth/debian/pi-bluetooth.bthelper@.service" "${ETC_DIR}/systemd/system/pi-bluetooth.bthelper@.service"
+    install_readonly "${R}/tmp/pi-bluetooth/debian/pi-bluetooth.hciuart.service" "${ETC_DIR}/systemd/system/pi-bluetooth.hciuart.service"
+    # Install udev rule for bluetooth device
+    install_readonly "${R}/tmp/pi-bluetooth/99-com.rules" "${ETC_DIR}/udev/rules.d/99-com.rules"
+	
+    # Remove temporary directory
+    rm -fr "${temp_dir}"
   fi
 fi
 
diff --git a/bootstrap.d/30-security.sh b/bootstrap.d/30-security.sh
index 5fbfc7a..8ad8275 100644
--- a/bootstrap.d/30-security.sh
+++ b/bootstrap.d/30-security.sh
@@ -11,8 +11,8 @@ ENCRYPTED_USER_PASSWORD=$(mkpasswd -m sha-512 "${USER_PASSWORD}")
 
 # Setup default user
 if [ "$ENABLE_USER" = true ] ; then
-  chroot_exec adduser --gecos $USER_NAME --add_extra_groups --disabled-password $USER_NAME
-  chroot_exec usermod -a -G sudo -p "${ENCRYPTED_USER_PASSWORD}" $USER_NAME
+  chroot_exec adduser --gecos "$USER_NAME" --add_extra_groups --disabled-password "$USER_NAME"
+  chroot_exec usermod -a -G sudo -p "${ENCRYPTED_USER_PASSWORD}" "$USER_NAME"
 fi
 
 # Setup root password or not
diff --git a/bootstrap.d/41-uboot.sh b/bootstrap.d/41-uboot.sh
index 6d42bde..c96b673 100644
--- a/bootstrap.d/41-uboot.sh
+++ b/bootstrap.d/41-uboot.sh
@@ -41,7 +41,7 @@ if [ "$ENABLE_UBOOT" = true ] ; then
 
   # Install and setup U-Boot command file
   install_readonly files/boot/uboot.mkimage "${BOOT_DIR}/uboot.mkimage"
-  printf "# Set the kernel boot command line\nsetenv bootargs \"earlyprintk ${CMDLINE}\"\n\n$(cat ${BOOT_DIR}/uboot.mkimage)" > "${BOOT_DIR}/uboot.mkimage"
+  printf "# Set the kernel boot command line\nsetenv bootargs \"earlyprintk ${CMDLINE}\"\n\n$(cat "${BOOT_DIR}"/uboot.mkimage)" > "${BOOT_DIR}/uboot.mkimage"
 
   if [ "$ENABLE_INITRAMFS" = true ] ; then
     # Convert generated initramfs for U-Boot using mkimage
@@ -51,7 +51,7 @@ if [ "$ENABLE_UBOOT" = true ] ; then
     rm -f "${BOOT_DIR}/initramfs-${KERNEL_VERSION}"
 
     # Configure U-Boot to load generated initramfs
-    printf "# Set initramfs file\nsetenv initramfs initramfs-${KERNEL_VERSION}.uboot\n\n$(cat ${BOOT_DIR}/uboot.mkimage)" > "${BOOT_DIR}/uboot.mkimage"
+    printf "# Set initramfs file\nsetenv initramfs initramfs-${KERNEL_VERSION}.uboot\n\n$(cat "${BOOT_DIR}"/uboot.mkimage)" > "${BOOT_DIR}/uboot.mkimage"
     printf "\nbootz \${kernel_addr_r} \${ramdisk_addr_r} \${fdt_addr_r}" >> "${BOOT_DIR}/uboot.mkimage"
   else # ENABLE_INITRAMFS=false
     # Remove initramfs from U-Boot mkfile
@@ -65,14 +65,16 @@ if [ "$ENABLE_UBOOT" = true ] ; then
       printf "\nbootz \${kernel_addr_r} - \${fdt_addr_r}" >> "${BOOT_DIR}/uboot.mkimage"
     fi
   fi
-  
-  if [ "$KERNEL_ARCH" = "arm64" ] ; then
-    echo "Setting up config.txt to boot 64bit uboot"
-
-    printf "\n# 64bit-mode" >> "${BOOT_DIR}/config.txt"
-    printf "\n# arm_control=0x200 is deprecated https://www.raspberrypi.org/documentation/configuration/config-txt/misc.md" >> "${BOOT_DIR}/config.txt"
-    printf "\narm_64bit=1" >> "${BOOT_DIR}/config.txt"
 
+  if [ "$SET_ARCH" = 64 ] ; then
+    echo "Setting up config.txt to boot 64bit uboot"
+    {
+      printf "\n# 64bit-mode"
+      printf "\n# arm_control=0x200 is deprecated https://www.raspberrypi.org/documentation/configuration/config-txt/misc.md"
+      printf "\narm_64bit=1"
+    } >> "${BOOT_DIR}/config.txt"
+    
+    #in 64bit uboot booti is used instead of bootz [like in KERNEL_BIN_IMAGE=zImage (armv7)|| Image(armv8)]
     sed -i "s|bootz|booti|g" "${BOOT_DIR}/uboot.mkimage"
   fi
 
diff --git a/bootstrap.d/43-videocore.sh b/bootstrap.d/43-videocore.sh
index d42590c..b8ff518 100644
--- a/bootstrap.d/43-videocore.sh
+++ b/bootstrap.d/43-videocore.sh
@@ -8,16 +8,16 @@
 if [ "$ENABLE_VIDEOCORE" = true ] ; then
   # Copy existing videocore sources into chroot directory
   if [ -n "$VIDEOCORESRC_DIR" ] && [ -d "$VIDEOCORESRC_DIR" ] ; then
-    # Copy local U-Boot sources
+    # Copy local videocore sources
     cp -r "${VIDEOCORESRC_DIR}" "${R}/tmp/userland"
   else
-    # Create temporary directory for U-Boot sources
+    # Create temporary directory for videocore sources
     temp_dir=$(as_nobody mktemp -d)
 
-    # Fetch U-Boot sources
+    # Fetch videocore sources
     as_nobody git -C "${temp_dir}" clone "${VIDEOCORE_URL}"
 
-    # Copy downloaded U-Boot sources
+    # Copy downloaded videocore sources
     mv "${temp_dir}/userland" "${R}/tmp/"
 
     # Set permissions of the U-Boot sources
@@ -31,7 +31,7 @@ if [ "$ENABLE_VIDEOCORE" = true ] ; then
   mkdir "${R}"/tmp/userland/build
 
   # push us to build directory
-  pushd "${R}"/tmp/userland/build
+  cd "${R}"/tmp/userland/build
 
   if [ "$RELEASE_ARCH" = "arm64" ] ; then
   cmake -DCMAKE_SYSTEM_NAME=Linux -DCMAKE_BUILD_TYPE=release -DARM64=ON -DCMAKE_C_COMPILER=aarch64-linux-gnu-gcc -DCMAKE_CXX_COMPILER=aarch64-linux-gnu-g++ -DCMAKE_ASM_COMPILER=aarch64-linux-gnu-gcc -DCMAKE_C_FLAGS="${CMAKE_C_FLAGS} -U_FORTIFY_SOURCE" -DCMAKE_ASM_FLAGS="${CMAKE_ASM_FLAGS} -c" -DVIDEOCORE_BUILD_DIR="${R}" "${R}/tmp/userland"
@@ -48,6 +48,6 @@ if [ "$ENABLE_VIDEOCORE" = true ] ; then
   #build userland
   make -j "$(nproc)"
 
-  #pop us out of build dir
-  popd
+  #back to root of scriptdir
+  cd "${WORKDIR}"
 fi
diff --git a/functions.sh b/functions.sh
index 6ee31da..74ca846 100644
--- a/functions.sh
+++ b/functions.sh
@@ -30,22 +30,22 @@ cleanup (){
 
 chroot_exec() {
   # Exec command in chroot
-  LANG=C LC_ALL=C DEBIAN_FRONTEND=noninteractive chroot ${R} $*
+  LANG=C LC_ALL=C DEBIAN_FRONTEND=noninteractive chroot "${R}" "$@"
 }
 
 as_nobody() {
   # Exec command as user nobody
-  sudo -E -u nobody LANG=C LC_ALL=C $*
+  sudo -E -u nobody LANG=C LC_ALL=C "$@"
 }
 
 install_readonly() {
   # Install file with user read-only permissions
-  install -o root -g root -m 644 $*
+  install -o root -g root -m 644 "$@"
 }
 
 install_exec() {
   # Install file with root exec permissions
-  install -o root -g root -m 744 $*
+  install -o root -g root -m 744 "$@"
 }
 
 use_template () {
@@ -64,14 +64,14 @@ chroot_install_cc() {
   if [ -z "${COMPILER_PACKAGES}" ] ; then
     COMPILER_PACKAGES=$(chroot_exec apt-get -s install g++ make bc | grep "^Inst " | awk -v ORS=" " '{ print $2 }')
 	# Install COMPILER_PACKAGES in chroot
-    chroot_exec apt-get -q -y --allow-unauthenticated --no-install-recommends install ${COMPILER_PACKAGES}
+    chroot_exec apt-get -q -y --allow-unauthenticated --no-install-recommends install "${COMPILER_PACKAGES}"
   fi
 }
 
 chroot_remove_cc() {
   # Remove c/c++ build environment from the chroot
-  if [ ! -z "${COMPILER_PACKAGES}" ] ; then
-    chroot_exec apt-get -qq -y --auto-remove purge ${COMPILER_PACKAGES}
+  if [ -n "${COMPILER_PACKAGES}" ] ; then
+    chroot_exec apt-get -qq -y --auto-remove purge "${COMPILER_PACKAGES}"
     COMPILER_PACKAGES=""
   fi
 }