diff --git a/build-docker.sh b/build-docker.sh
index cb30c52..71e52f8 100755
--- a/build-docker.sh
+++ b/build-docker.sh
@@ -3,28 +3,29 @@
 BUILD_OPTS="$*"
 
 DOCKER="docker"
-set +e
-if ! $DOCKER ps >/dev/null 2>&1; then
+
+if ! ${DOCKER} ps >/dev/null 2>&1; then
 	DOCKER="sudo docker"
 fi
-if ! $DOCKER ps >/dev/null; then
+if ! ${DOCKER} ps >/dev/null; then
 	echo "error connecting to docker:"
-	$DOCKER ps
+	${DOCKER} ps
 	exit 1
 fi
-set -e
 
-if [ -f config ]; then
+CONFIG_FILE="${DIR}/config"
+if [ -f "${CONFIG_FILE}" ]; then
 	# shellcheck disable=SC1091
-	source config
+	source "${CONFIG_FILE}"
 fi
 
 while getopts "c:" flag
 do
-	case "$flag" in
+	case "${flag}" in
 		c)
 			# shellcheck disable=SC1090
-			source "$OPTARG"
+			source "${OPTARG}"
+			CONFIG_FILE="${OPTARG}"
 			;;
 		*)
 			;;
@@ -41,23 +42,23 @@ if [ -z "${IMG_NAME}" ]; then
 exit 1
 fi
 
-CONTAINER_EXISTS=$($DOCKER ps -a --filter name="$CONTAINER_NAME" -q)
-CONTAINER_RUNNING=$($DOCKER ps --filter name="$CONTAINER_NAME" -q)
-if [ "$CONTAINER_RUNNING" != "" ]; then
-	echo "The build is already running in container $CONTAINER_NAME. Aborting."
+CONTAINER_EXISTS=$(${DOCKER} ps -a --filter name="${CONTAINER_NAME}" -q)
+CONTAINER_RUNNING=$(${DOCKER} ps --filter name="${CONTAINER_NAME}" -q)
+if [ "${CONTAINER_RUNNING}" != "" ]; then
+	echo "The build is already running in container ${CONTAINER_NAME}. Aborting."
 	exit 1
 fi
-if [ "$CONTAINER_EXISTS" != "" ] && [ "$CONTINUE" != "1" ]; then
-	echo "Container $CONTAINER_NAME already exists and you did not specify CONTINUE=1. Aborting."
+if [ "${CONTAINER_EXISTS}" != "" ] && [ "${CONTINUE}" != "1" ]; then
+	echo "Container ${CONTAINER_NAME} already exists and you did not specify CONTINUE=1. Aborting."
 	echo "You can delete the existing container like this:"
-	echo "  $DOCKER rm -v $CONTAINER_NAME"
+	echo "  ${DOCKER} rm -v ${CONTAINER_NAME}"
 	exit 1
 fi
 
-$DOCKER build -t pi-gen .
-if [ "$CONTAINER_EXISTS" != "" ]; then
-	trap 'echo "got CTRL+C... please wait 5s"; $DOCKER stop -t 5 ${CONTAINER_NAME}_cont' SIGINT SIGTERM
-	time $DOCKER run --rm --privileged \
+${DOCKER} build -t pi-gen .
+if [ "${CONTAINER_EXISTS}" != "" ]; then
+	trap 'echo "got CTRL+C... please wait 5s" && ${DOCKER} stop -t 5 ${CONTAINER_NAME}_cont' SIGINT SIGTERM
+	time ${DOCKER} run --rm --privileged \
 		--volumes-from="${CONTAINER_NAME}" --name "${CONTAINER_NAME}_cont" \
 		pi-gen \
 		bash -e -o pipefail -c "dpkg-reconfigure qemu-user-static &&
@@ -65,8 +66,8 @@ if [ "$CONTAINER_EXISTS" != "" ]; then
 	rsync -av work/*/build.log deploy/" &
 	wait "$!"
 else
-	trap 'echo "got CTRL+C... please wait 5s"; $DOCKER stop -t 5 ${CONTAINER_NAME}' SIGINT SIGTERM
-	time $DOCKER run --name "${CONTAINER_NAME}" --privileged \
+	trap 'echo "got CTRL+C... please wait 5s" && ${DOCKER} stop -t 5 ${CONTAINER_NAME}' SIGINT SIGTERM
+	time ${DOCKER} run --name "${CONTAINER_NAME}" --privileged \
 		pi-gen \
 		bash -e -o pipefail -c "dpkg-reconfigure qemu-user-static &&
 	cd /pi-gen; ./build.sh ${BUILD_OPTS} &&
@@ -74,12 +75,12 @@ else
 	wait "$!"
 fi
 echo "copying results from deploy/"
-$DOCKER cp "${CONTAINER_NAME}":/pi-gen/deploy .
+${DOCKER} cp "${CONTAINER_NAME}":/pi-gen/deploy .
 ls -lah deploy
 
 # cleanup
-if [ "$PRESERVE_CONTAINER" != "1" ]; then
-	$DOCKER rm -v "$CONTAINER_NAME"
+if [ "${PRESERVE_CONTAINER}" != "1" ]; then
+	${DOCKER} rm -v "${CONTAINER_NAME}"
 fi
 
 echo "Done! Your image(s) should be in deploy/"