diff --git a/scripts/cloudron-setup b/scripts/cloudron-setup
index 56908fa61..349e1b5cb 100755
--- a/scripts/cloudron-setup
+++ b/scripts/cloudron-setup
@@ -15,7 +15,7 @@ fi
 # change this to a hash when we make a upgrade release
 readonly LOG_FILE="/var/log/cloudron-setup.log"
 readonly DATA_FILE="/root/cloudron-install-data.json"
-readonly MINIMUM_DISK_SIZE_GB="19" # this is the size of "/" and required to fit in docker images 19 is a safe bet for different reporting on 20GB min
+readonly MINIMUM_DISK_SIZE_GB="18" # this is the size of "/" and required to fit in docker images 18 is a safe bet for different reporting on 20GB min
 readonly MINIMUM_MEMORY="974"      # this is mostly reported for 1GB main memory (DO 992, EC2 990, Linode 989, Serverdiscounter.com 974)
 
 readonly curl="curl --fail --connect-timeout 20 --retry 10 --retry-delay 2 --max-time 2400"
@@ -23,8 +23,8 @@ readonly curl="curl --fail --connect-timeout 20 --retry 10 --retry-delay 2 --max
 # copied from cloudron-resize-fs.sh
 readonly physical_memory=$(LC_ALL=C free -m | awk '/Mem:/ { print $2 }')
 readonly disk_device="$(for d in $(find /dev -type b); do [ "$(mountpoint -d /)" = "$(mountpoint -x $d)" ] && echo $d && break; done)"
-readonly disk_size_bytes=$(LC_ALL=C fdisk -l ${disk_device} | grep "Disk ${disk_device}" | awk '{ printf $5 }')
-readonly disk_size_gb=$((${disk_size_bytes}/1024/1024/1024))
+readonly disk_size_bytes=$(LC_ALL=C df | grep "${disk_device}" | awk '{ printf $2 }')
+readonly disk_size_gb=$((${disk_size_bytes}/1024/1024))
 
 # verify the system has minimum requirements met
 if [[ "${physical_memory}" -lt "${MINIMUM_MEMORY}" ]]; then
diff --git a/setup/start/cloudron-resize-fs.sh b/setup/start/cloudron-resize-fs.sh
index ee7bdc604..63f16ba8a 100755
--- a/setup/start/cloudron-resize-fs.sh
+++ b/setup/start/cloudron-resize-fs.sh
@@ -16,8 +16,8 @@ existing_swap=$(cat /proc/meminfo | grep SwapTotal | awk '{ printf "%.0f", $2/10
 readonly physical_memory=$(LC_ALL=C free -m | awk '/Mem:/ { print $2 }')
 readonly swap_size=$((${physical_memory} - ${existing_swap})) # if you change this, fix enoughResourcesAvailable() in client.js
 readonly app_count=$((${physical_memory} / 200)) # estimated app count
-readonly disk_size_bytes=$(LC_ALL=C fdisk -l ${disk_device} | grep "Disk ${disk_device}" | awk '{ printf $5 }') # can't rely on fdisk human readable units, using bytes instead
-readonly disk_size=$((${disk_size_bytes}/1024/1024))
+readonly disk_size_bytes=$(LC_ALL=C df | grep "${disk_device}" | awk '{ printf $2 }')
+readonly disk_size=$((${disk_size_bytes}/1024))
 readonly system_size=10240 # 10 gigs for system libs, apps images, installer, box code, data and tmp
 readonly ext4_reserved=$((disk_size * 5 / 100)) # this can be changes using tune2fs -m percent /dev/vda1