diff --git a/board/raspberrypi/post-image.sh b/board/raspberrypi/post-image.sh
index a2d6a98e79..3c6c938407 100755
--- a/board/raspberrypi/post-image.sh
+++ b/board/raspberrypi/post-image.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -e
+
 BOARD_DIR="$(dirname $0)"
 BOARD_NAME="$(basename ${BOARD_DIR})"
 GENIMAGE_CFG="${BOARD_DIR}/genimage-${BOARD_NAME}.cfg"
@@ -40,7 +42,7 @@ __EOF__
 		;;
 		--gpu_mem_256=*|--gpu_mem_512=*|--gpu_mem_1024=*)
 		# Set GPU memory
-		gpu_mem="${1:2}"
+		gpu_mem="${arg:2}"
 		sed -e "/^${gpu_mem%=*}=/s,=.*,=${gpu_mem##*=}," -i "${BINARIES_DIR}/rpi-firmware/config.txt"
 		;;
 	esac