diff --git a/generate-unique-machine-values.sh b/generate-unique-machine-values.sh
index 0e53dbd..d62b1f8 100755
--- a/generate-unique-machine-values.sh
+++ b/generate-unique-machine-values.sh
@@ -337,7 +337,7 @@ EOF
                 mkdir -p "${OUTPUT_DIRECTORY}/plists"
                 source "${OUTPUT_ENV_FILE}"
                 ROM="${MAC_ADDRESS//\:/}"
-                ROM="${ROM,,}"
+                ROM=$(echo ${ROM} |  awk '{print tolower($0)}')
                 sed -e s/\{\{DEVICE_MODEL\}\}/"${DEVICE_MODEL}"/g \
                     -e s/\{\{SERIAL\}\}/"${SERIAL}"/g \
                     -e s/\{\{BOARD_SERIAL\}\}/"${BOARD_SERIAL}"/g \