diff --git a/deployment_scripts/puppet/modules/disk_management/files/add_partition.sh b/deployment_scripts/puppet/modules/disk_management/files/add_partition.sh
index aaeba0a..ceb345f 100644
--- a/deployment_scripts/puppet/modules/disk_management/files/add_partition.sh
+++ b/deployment_scripts/puppet/modules/disk_management/files/add_partition.sh
@@ -14,28 +14,28 @@ DISK_SIZE=${2:-""}
 
 PARTED="$(which parted 2>/dev/null) -s -m"
 
-if ${PARTED} ${DISK} p | grep -q "unrecognised disk label"; then
+if ${PARTED} "${DISK}" p | grep -q "unrecognised disk label"; then
     # We need to create a new label
-    ${PARTED} ${DISK} mklabel gpt
+    ${PARTED} "${DISK}" mklabel gpt
 fi
 
 # We take the free space at the end of the disk.
-FREESPACE=$(${PARTED} ${DISK} unit B p free | grep "free" | tail -1)
+FREESPACE=$(${PARTED} "${DISK}" unit B p free | grep "free" | tail -1)
 if [[ -z "${FREESPACE}" ]]; then
     echo "Failed to find free space"
     exit 1
 fi
 
-BEGIN=$(echo ${FREESPACE} | awk -F: '{print $2}')
-if [ -z ${DISK_SIZE} ]; then
-    END=$(echo ${FREESPACE} | awk -F: '{print $3}')
+BEGIN=$(echo "${FREESPACE}" | awk -F: '{print $2}')
+if [ -z "${DISK_SIZE}" ]; then
+    END=$(echo "${FREESPACE}" | awk -F: '{print $3}')
 else
-    END="$(( $(echo $BEGIN | rev | cut -c 2- | rev) + $(( ${DISK_SIZE}*1024*1024*1024 )) ))B"
+    END="$(( $(echo "$BEGIN" | rev | cut -c 2- | rev) + $(( DISK_SIZE*1024*1024*1024 )) ))B"
 fi
 
 # If you create a partition on a mounted disk, this command returns 1
 # So we need a different way to catch the error
-if ${PARTED} ${DISK} unit B mkpart primary ${BEGIN} ${END} | grep -q "^Error"; then
+if ${PARTED} "${DISK}" unit B mkpart primary "${BEGIN}" "${END}" | grep -q "^Error"; then
     echo "Failed to create a new primary partition"
     exit 1
 fi
@@ -44,8 +44,8 @@ fi
 # Like when we create a new partition, if you run this command on a mounted
 # FS the kernel failed to re-read the partition and the command returns 1
 # event in case of success.
-PARTID=$(${PARTED} ${DISK} p | tail -1 | awk -F: {'print $1'})
-if ${PARTED} ${DISK} set ${PARTID} lvm on | grep -q "^Error"; then
+PARTID=$(${PARTED} "${DISK}" p | tail -1 | awk -F: '{print $1}')
+if ${PARTED} "${DISK}" set "${PARTID}" lvm on | grep -q "^Error"; then
     echo "Failed to set the lvm flag on partition ${PARTID}."
     exit 1
 fi
diff --git a/pre_build_hook b/pre_build_hook
index a853188..7b6af63 100755
--- a/pre_build_hook
+++ b/pre_build_hook
@@ -1,7 +1,7 @@
 #!/bin/bash
 set -eux
 
-ROOT="$(dirname `readlink -f $0`)"
+ROOT="$(dirname "$(readlink -f "$0")")"
 MODULES="${ROOT}"/deployment_scripts/puppet/modules
 RPM_REPO="${ROOT}"/repositories/centos/
 DEB_REPO="${ROOT}"/repositories/ubuntu/
@@ -26,8 +26,8 @@ function download {
     shift
 
     while [ $# -gt 0 ]; do
-        FILE=$(basename $1)
-        wget -qO - $1 > $REPO/$FILE
+        FILE=$(basename "$1")
+        wget -qO - "$1" > "$REPO/$FILE"
         shift
     done
 }
@@ -48,8 +48,8 @@ download rpm http://mirror.centos.org/centos/6/updates/x86_64/Packages/java-1.8.
 
 # Install puppet manifests
 # Clean-up first
-rm -rf ${MODULES}/{stdlib,concat,lvm,elasticsearch,nginx}
-mkdir -p ${MODULES}/{elasticsearch,nginx}
+rm -rf "${MODULES:?}"/{stdlib,concat,lvm,elasticsearch,nginx}
+mkdir -p "${MODULES}"/{elasticsearch,nginx}
 
 # Include elasticsearch and nginx manifests from puppetlabs
 wget -qO- "${ELASTICSEARCH_TARBALL_URL}" | tar -C "${MODULES}/elasticsearch" --strip-components=1 -xz
@@ -62,5 +62,5 @@ wget -qO- "${FUEL_LIB_TARBALL_URL}" | \
 
 # Untar kibana
 KIBANA_FOLDER="${MODULES}/lma_logging_analytics/files/kibana/src"
-mkdir -p ${KIBANA_FOLDER}
+mkdir -p "${KIBANA_FOLDER}"
 wget -qO- "${KIBANA_TARBALL_URL}" | tar -C "${KIBANA_FOLDER}" --strip-components=1 -xz