diff --git a/src/pvmboot.sh b/src/pvmboot.sh
index abebdbb..2eddc72 100644
--- a/src/pvmboot.sh
+++ b/src/pvmboot.sh
@@ -21,13 +21,15 @@
 # shellcheck source=/usr/lib/libretools/messages.sh
 source "$(librelib messages)"
 
+readonly DEF_RAM_MB=1000
+
 
 usage() {
   print "USAGE: %s [-h] <img> [qemu-args ...]" "${0##*/}"
   prose "Determine the architecture of <img> and boot it using qemu. <img> is assumed
          to be a valid, raw-formatted parabola virtual machine image, ideally
-         created using pvmbootstrap. The started instance is assigned 1G of
-         RAM and one SMP core."
+         created using pvmbootstrap. The started instance is assigned
+         ${DEF_RAM_MB}MB of RAM and one SMP core."
   echo
   prose "When a graphical desktop environment is available, start the machine
          normally, otherwise append -nographic to the qemu options. This behavior
@@ -129,13 +131,13 @@ pvm_guess_qemu_args() {
   local kernel_console
   case "$2" in
     i386|x86_64|ppc64)
-      qemu_args+=(-m 1G -hda "$1")
+      qemu_args+=(-m $DEF_RAM_MB -hda "$1")
       # unmount the unneeded virtual drive early
       pvm_umount ;;
     arm)
       kernel_console="console=tty0 console=ttyAMA0 "
       qemu_args+=(-machine virt
-                  -m       1G
+                  -m       $DEF_RAM_MB
                   -kernel  "$workdir"/vmlinuz-linux-libre
                   -initrd  "$workdir"/initramfs-linux-libre.img
                   -append  "${kernel_console}rw root=/dev/vda3"
@@ -146,7 +148,7 @@ pvm_guess_qemu_args() {
     riscv64)
       kernel_console=$( [ -z "$DISPLAY" ] && echo "console=ttyS0 " )
       qemu_args+=(-machine virt
-                  -m       1G
+                  -m       $DEF_RAM_MB
                   -kernel  "$workdir"/bbl
                   -append  "${kernel_console}rw root=/dev/vda"
                   -drive   "file=${loopdev}p3,format=raw,id=hd0"
diff --git a/src/pvmbootstrap.sh b/src/pvmbootstrap.sh
index 442d1da..b7e20a8 100644
--- a/src/pvmbootstrap.sh
+++ b/src/pvmbootstrap.sh
@@ -52,7 +52,7 @@ usage() {
   echo  "  -M <mirror>     Specify a different mirror from which to fetch packages"
   echo  "                  (default: $DEF_MIRROR)"
   echo  "  -O              Bootstrap an openrc system instead of a systemd one"
-  echo  "  -s <img_size>   Set the size (in GB) of the VM image (default: $DEF_IMG_GB)"
+  echo  "  -s <img_size>   Set the size (in GB) of the VM image (minimum: $MIN_GB, default: $DEF_IMG_GB)"
   echo
   echo  "Pre-defined hooks:"
   echo  "  ethernet-dhcp:  Configure and enable an ethernet device in the virtual"
@@ -390,9 +390,10 @@ main() {
 
   local shiftlen=$(( OPTIND - 1 ))
   shift $shiftlen
-  if [ "$#" -ne 2 ]; then usage >&2; exit "$EXIT_INVALIDARGUMENT"; fi
   local file="$1"
   local arch="$2"
+  [ "$#" -ne 2               ] && usage >&2 && exit "$EXIT_INVALIDARGUMENT"
+  [ "$ImgSizeGb" -lt $MIN_GB ] && usage >&2 && exit "$EXIT_INVALIDARGUMENT"
 
   # determine if the target arch is supported
   case "$arch" in