diff --git a/flash/FP4/flash_FP4_factory.sh b/flash/FP4/flash_FP4_factory.sh
index 1a7cc1093281b4691ab318d4f74dc5943a8c44dc..fa35ef46f4929880ad02c2778040085732d591e6 100755
--- a/flash/FP4/flash_FP4_factory.sh
+++ b/flash/FP4/flash_FP4_factory.sh
@@ -37,10 +37,10 @@ find_device() {
   do
     serial_numbers=
 
-    for sn in $(${FASTBOOT_BIN} devices | grep fastboot | grep -oE '^[[:alnum:]]+')
+    for sn in $("${FASTBOOT_BIN}" devices | grep fastboot | grep -oE '^[[:alnum:]]+')
     do
       # Checking the product ID
-      PRODUCT_STRING=$(${FASTBOOT_BIN} -s "${sn}" getvar product 2>&1)
+      PRODUCT_STRING=$("${FASTBOOT_BIN}" -s "${sn}" getvar product 2>&1)
       # Add serial, if product matches
       if [[ ${PRODUCT_STRING} == *"${PRODUCT_ID}"* ]] || [[ ${PRODUCT_STRING} == *"${PRODUCT_ID_OLD}"* ]]
       then
@@ -111,10 +111,10 @@ flash_device() {
   flash_image_ab_or_abort "${sn}" xbl_config "${IMAGES_DIR}/xbl_config.img"
   flash_image_ab_or_abort "${sn}" core_nhlos "${IMAGES_DIR}/core_nhlos.img"
 
-  $FASTBOOT_BIN -s "${sn}" erase userdata
-  $FASTBOOT_BIN -s "${sn}" erase metadata
+  "$FASTBOOT_BIN" -s "${sn}" erase userdata
+  "$FASTBOOT_BIN" -s "${sn}" erase metadata
 
-  $FASTBOOT_BIN -s "${sn}" --set-active=a
+  "$FASTBOOT_BIN" -s "${sn}" --set-active=a
 
 }
 
@@ -122,7 +122,7 @@ flash_device() {
 # Arguments: <device serial number> <partition name> <image file>
 flash_image_or_abort() {
   local retval=0
-  $FASTBOOT_BIN -s "${1}" flash "${2}" "${3}" || retval=$?
+  "$FASTBOOT_BIN" -s "${1}" flash "${2}" "${3}" || retval=$?
 
   if [ "${retval}" -ne 0 ]
   then