diff --git a/chip-fel-fastboot.sh b/chip-fel-fastboot.sh
index ffeafb6..6491519 100755
--- a/chip-fel-fastboot.sh
+++ b/chip-fel-fastboot.sh
@@ -35,8 +35,8 @@ prepare_images() {
 	local in=$SPL
 	local out=$PADDED_SPL
 
-	if [ -e $out ]; then
-		rm $out
+	if [ -e "$out" ]; then
+		rm "$out"
 	fi
 
 	# The BROM cannot read 16K pages: it only reads 8k of data at most.
@@ -59,33 +59,33 @@ prepare_images() {
 
 prepare_uboot_script() {
 	if [ "$NAND_ERASE_BB" = true ] ; then
-		echo "nand scrub -y 0x0 0x200000000" > $UBOOT_SCRIPT_SRC
+		echo "nand scrub -y 0x0 0x200000000" > "${UBOOT_SCRIPT_SRC}"
 	else
-		echo "nand erase 0x0 0x200000000" > $UBOOT_SCRIPT_SRC
+		echo "nand erase 0x0 0x200000000" > "${UBOOT_SCRIPT_SRC}"
 	fi
-	echo "sunxi_nand config spl" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x100000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x200000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x300000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x500000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x600000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $SPL_MEM_ADDR 0x700000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "sunxi_nand config default" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $UBOOT_MEM_ADDR 0x800000 $PADDED_UBOOT_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "setenv bootargs root=ubi0:rootfs rootfstype=ubifs rw earlyprintk ubi.mtd=4" >> $UBOOT_SCRIPT_SRC
-	echo "setenv bootcmd 'source \${scriptaddr}; nand slc-mode on; mtdparts; ubi part UBI; ubifsmount ubi0:rootfs; ubifsload \$fdt_addr_r /boot/sun5i-r8-chip.dtb; ubifsload \$kernel_addr_r /boot/zImage; bootz \$kernel_addr_r - \$fdt_addr_r'" >> $UBOOT_SCRIPT_SRC
-	echo "saveenv" >> $UBOOT_SCRIPT_SRC
+	echo "sunxi_nand config spl" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x100000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x200000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x300000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x500000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x600000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $SPL_MEM_ADDR 0x700000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "sunxi_nand config default" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $UBOOT_MEM_ADDR 0x800000 $PADDED_UBOOT_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "setenv bootargs root=ubi0:rootfs rootfstype=ubifs rw earlyprintk ubi.mtd=4" >> "${UBOOT_SCRIPT_SRC}"
+	echo "setenv bootcmd 'source \${scriptaddr}; nand slc-mode on; mtdparts; ubi part UBI; ubifsmount ubi0:rootfs; ubifsload \$fdt_addr_r /boot/sun5i-r8-chip.dtb; ubifsload \$kernel_addr_r /boot/zImage; bootz \$kernel_addr_r - \$fdt_addr_r'" >> "${UBOOT_SCRIPT_SRC}"
+	echo "saveenv" >> "${UBOOT_SCRIPT_SRC}"
 
-  echo "echo going to fastboot mode" >>$UBOOT_SCRIPT_SRC
-  echo "fastboot" >>$UBOOT_SCRIPT_SRC
-  echo "echo " >>$UBOOT_SCRIPT_SRC
-  echo "echo *****************[ BOOT ]*****************" >>$UBOOT_SCRIPT_SRC
-  echo "echo " >>$UBOOT_SCRIPT_SRC
-  echo "boot" >>$UBOOT_SCRIPT_SRC
+  echo "echo going to fastboot mode" >>"${UBOOT_SCRIPT_SRC}"
+  echo "fastboot" >>"${UBOOT_SCRIPT_SRC}"
+  echo "echo " >>"${UBOOT_SCRIPT_SRC}"
+  echo "echo *****************[ BOOT ]*****************" >>"${UBOOT_SCRIPT_SRC}"
+  echo "echo " >>"${UBOOT_SCRIPT_SRC}"
+  echo "boot" >>"${UBOOT_SCRIPT_SRC}"
 
-	mkimage -A arm -T script -C none -n "flash CHIP" -d $UBOOT_SCRIPT_SRC $UBOOT_SCRIPT
+	mkimage -A arm -T script -C none -n "flash CHIP" -d "$UBOOT_SCRIPT_SRC" "$UBOOT_SCRIPT"
 }
 
 wait_for_fastboot() {
@@ -113,20 +113,20 @@ ${FEL} spl $SPL
 sleep 1 # wait for DRAM initialization to complete
 
 echo == upload spl ==
-${FEL} write $SPL_MEM_ADDR $PADDED_SPL
+${FEL} write $SPL_MEM_ADDR "$PADDED_SPL"
 echo == upload u-boot ==
-${FEL} write $UBOOT_MEM_ADDR $PADDED_UBOOT
+${FEL} write $UBOOT_MEM_ADDR "$PADDED_UBOOT"
 echo == upload u-boot script ==
-${FEL} write $UBOOT_SCRIPT_MEM_ADDR $UBOOT_SCRIPT
+${FEL} write $UBOOT_SCRIPT_MEM_ADDR "$UBOOT_SCRIPT"
 
 echo == execute the main u-boot binary ==
 ${FEL} exe $UBOOT_MEM_ADDR
 
 echo == waiting for fastboot ==
 if wait_for_fastboot; then
-  fastboot -S 0 -u flash UBI ${BUILDROOT_OUTPUT_DIR}/images/rootfs.ubi
+  fastboot -S 0 -u flash UBI "${BUILDROOT_OUTPUT_DIR}/images/rootfs.ubi"
   fastboot continue
 else
-  rm -rf ${TMPDIR}
+  rm -rf "${TMPDIR}"
   exit 1
 fi
diff --git a/chip-fel-flash.sh b/chip-fel-flash.sh
index 5f25982..291ba51 100755
--- a/chip-fel-flash.sh
+++ b/chip-fel-flash.sh
@@ -42,63 +42,61 @@ prepare_images() {
 		rm $out
 	fi
 
-  echo ${SCRIPTDIR}/spl-image-builder -d -r 3 -u 4096 -o 1664 -p 16384 -c 1024 -s 64 $in $out
-
-  if [[ ! -e ${SCRIPTDIR}/spl-image-builder ]]; then
-    pushd ${SCRIPTDIR}
+  if [[ ! -e "${SCRIPTDIR}/spl-image-builder" ]]; then
+    pushd "${SCRIPTDIR}"
     make
     popd
   fi
 
-  ${SCRIPTDIR}/spl-image-builder -d -r 3 -u 4096 -o 1664 -p 16384 -c 1024 -s 64 $in $out
+  "${SCRIPTDIR}/spl-image-builder" -d -r 3 -u 4096 -o 1664 -p 16384 -c 1024 -s 64 "$in" "$out"
 
   #PADDED_SPL_SIZE in pages
-	PADDED_SPL_SIZE=$(filesize $out)
+	PADDED_SPL_SIZE=$(filesize "$out")
   PADDED_SPL_SIZE=$(($PADDED_SPL_SIZE / ($PAGE_SIZE + $OOB_SIZE)))
   PADDED_SPL_SIZE=$(echo $PADDED_SPL_SIZE | xargs printf "0x%08x")
-  echo "filesize= $(filesize $out)"
+  echo "filesize= $(filesize "$out")"
   echo "PADDED_SPL_SIZE=$PADDED_SPL_SIZE"
 
 	# Align the u-boot image on a page boundary
-	dd if=$UBOOT of=$PADDED_UBOOT bs=16k conv=sync
-	UBOOT_SIZE=`filesize $PADDED_UBOOT | xargs printf "0x%08x"`
-	dd if=/dev/urandom of=$PADDED_UBOOT seek=$((UBOOT_SIZE / 0x4000)) bs=16k count=$(((PADDED_UBOOT_SIZE - UBOOT_SIZE) / 0x4000))
+	dd if="$UBOOT" of="$PADDED_UBOOT" bs=16k conv=sync
+	UBOOT_SIZE=`filesize "$PADDED_UBOOT" | xargs printf "0x%08x"`
+	dd if=/dev/urandom of="$PADDED_UBOOT" seek=$((UBOOT_SIZE / 0x4000)) bs=16k count=$(((PADDED_UBOOT_SIZE - UBOOT_SIZE) / 0x4000))
 }
 
 prepare_uboot_script() {
 	if [ "$NAND_ERASE_BB" = true ] ; then
-		echo "nand scrub -y 0x0 0x200000000" > $UBOOT_SCRIPT_SRC
+		echo "nand scrub -y 0x0 0x200000000" > "${UBOOT_SCRIPT_SRC}"
 	else
-		echo "nand erase 0x0 0x200000000" > $UBOOT_SCRIPT_SRC
+		echo "nand erase 0x0 0x200000000" > "${UBOOT_SCRIPT_SRC}"
 	fi
-	echo "echo sunxi_nand config spl" >> $UBOOT_SCRIPT_SRC
-  echo "sunxi_nand config spl" >> $UBOOT_SCRIPT_SRC
-	echo "echo nand write.raw $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write.raw $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "echo nand write.raw $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "nand write.raw $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "sunxi_nand config default" >> $UBOOT_SCRIPT_SRC
-	echo "nand write $UBOOT_MEM_ADDR 0x800000 $PADDED_UBOOT_SIZE" >> $UBOOT_SCRIPT_SRC
-	echo "setenv bootargs root=ubi0:rootfs rootfstype=ubifs rw earlyprintk ubi.mtd=4" >> $UBOOT_SCRIPT_SRC
-	echo "setenv bootcmd 'source \${scriptaddr}; nand slc-mode on; mtdparts; ubi part UBI; ubifsmount ubi0:rootfs; ubifsload \$fdt_addr_r /boot/sun5i-r8-chip.dtb; ubifsload \$kernel_addr_r /boot/zImage; bootz \$kernel_addr_r - \$fdt_addr_r'" >> $UBOOT_SCRIPT_SRC
-	echo "saveenv" >> $UBOOT_SCRIPT_SRC
+	echo "echo sunxi_nand config spl" >> "${UBOOT_SCRIPT_SRC}"
+  echo "sunxi_nand config spl" >> "${UBOOT_SCRIPT_SRC}"
+	echo "echo nand write.raw $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write.raw $SPL_MEM_ADDR 0x0 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "echo nand write.raw $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write.raw $SPL_MEM_ADDR 0x400000 $PADDED_SPL_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "sunxi_nand config default" >> "${UBOOT_SCRIPT_SRC}"
+	echo "nand write $UBOOT_MEM_ADDR 0x800000 $PADDED_UBOOT_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	echo "setenv bootargs root=ubi0:rootfs rootfstype=ubifs rw earlyprintk ubi.mtd=4" >> "${UBOOT_SCRIPT_SRC}"
+	echo "setenv bootcmd 'source \${scriptaddr}; nand slc-mode on; mtdparts; ubi part UBI; ubifsmount ubi0:rootfs; ubifsload \$fdt_addr_r /boot/sun5i-r8-chip.dtb; ubifsload \$kernel_addr_r /boot/zImage; bootz \$kernel_addr_r - \$fdt_addr_r'" >> "${UBOOT_SCRIPT_SRC}"
+	echo "saveenv" >> "${UBOOT_SCRIPT_SRC}"
 
   if [[ "${METHOD}" == "fel" ]]; then
-	  echo "nand slc-mode on" >> $UBOOT_SCRIPT_SRC
-	  echo "nand write.trimffs $UBI_MEM_ADDR 0x1000000 $UBI_SIZE" >> $UBOOT_SCRIPT_SRC
-	  echo "mw \${scriptaddr} 0x0" >> $UBOOT_SCRIPT_SRC
-	  echo "boot" >> $UBOOT_SCRIPT_SRC
+	  echo "nand slc-mode on" >> "${UBOOT_SCRIPT_SRC}"
+	  echo "nand write.trimffs $UBI_MEM_ADDR 0x1000000 $UBI_SIZE" >> "${UBOOT_SCRIPT_SRC}"
+	  echo "mw \${scriptaddr} 0x0" >> "${UBOOT_SCRIPT_SRC}"
+	  echo "boot" >> "${UBOOT_SCRIPT_SRC}"
   else
-    echo "echo going to fastboot mode" >>$UBOOT_SCRIPT_SRC
-    echo "fastboot" >>$UBOOT_SCRIPT_SRC
-    echo "echo " >>$UBOOT_SCRIPT_SRC
-    echo "echo *****************[ BOOT ]*****************" >>$UBOOT_SCRIPT_SRC
-    echo "echo " >>$UBOOT_SCRIPT_SRC
-    echo "echo " >>$UBOOT_SCRIPT_SRC
-    echo "boot" >>$UBOOT_SCRIPT_SRC
+    echo "echo going to fastboot mode" >>"${UBOOT_SCRIPT_SRC}"
+    echo "fastboot" >>"${UBOOT_SCRIPT_SRC}"
+    echo "echo " >>"${UBOOT_SCRIPT_SRC}"
+    echo "echo *****************[ BOOT ]*****************" >>"${UBOOT_SCRIPT_SRC}"
+    echo "echo " >>"${UBOOT_SCRIPT_SRC}"
+    echo "echo " >>"${UBOOT_SCRIPT_SRC}"
+    echo "boot" >>"${UBOOT_SCRIPT_SRC}"
   fi
 
-	mkimage -A arm -T script -C none -n "flash CHIP" -d $UBOOT_SCRIPT_SRC $UBOOT_SCRIPT
+	mkimage -A arm -T script -C none -n "flash CHIP" -d "${UBOOT_SCRIPT_SRC}" "${UBOOT_SCRIPT}"
 }
 
 
@@ -127,22 +125,22 @@ echo == upload the SPL to SRAM and execute it ==
 if ! wait_for_fel; then
   echo "ERROR: please make sure CHIP is connected and jumpered in FEL mode"
 fi
-${FEL} spl $SPL
+${FEL} spl "${SPL}"
 
 sleep 1 # wait for DRAM initialization to complete
 
 echo == upload spl ==
-${FEL} write $SPL_MEM_ADDR $PADDED_SPL
+${FEL} write $SPL_MEM_ADDR "${PADDED_SPL}"
 
 echo == upload u-boot ==
-${FEL} write $UBOOT_MEM_ADDR $PADDED_UBOOT 
+${FEL} write $UBOOT_MEM_ADDR "${PADDED_UBOOT}"
 
 echo == upload u-boot script ==
-${FEL} write $UBOOT_SCRIPT_MEM_ADDR $UBOOT_SCRIPT
+${FEL} write $UBOOT_SCRIPT_MEM_ADDR "${UBOOT_SCRIPT}"
 
 if [[ "${METHOD}" == "fel" ]]; then
   echo == upload ubi ==
-  ${FEL} --progress write $UBI_MEM_ADDR $UBI 
+  ${FEL} --progress write $UBI_MEM_ADDR "${UBI}"
 
   echo == execute the main u-boot binary ==
   ${FEL} exe $UBOOT_MEM_ADDR
@@ -157,9 +155,9 @@ else
     fastboot -S 0 -u flash UBI ${BUILDROOT_OUTPUT_DIR}/images/rootfs.ubi
     fastboot continue
   else
-    rm -rf ${TMPDIR}
+    rm -rf "${TMPDIR}"
     exit 1
   fi
 fi
 
-rm -rf ${TMPDIR}
+rm -rf "${TMPDIR}"