diff --git a/README.md b/README.md
index 280cc44..92f34b7 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ Devuan Linux for Windows users
 # How to "build"
 ## Prerequisites
 - You need to use Devuan or windvn
-- `apt install debootstrap isolinux syslinux-common xorriso`
+- `apt install debootstrap isolinux syslinux-common squashfs-tools xorriso`
 ---
 1. **Get into the windvn environment:**
 ```
diff --git a/path/wdvn-image-iso b/path/wdvn-image-iso
index e96c504..745e88c 100755
--- a/path/wdvn-image-iso
+++ b/path/wdvn-image-iso
@@ -30,6 +30,12 @@ if [ ! -f "$CHROOT/usr/share/initramfs-tools/hooks/live" ]; then
 	EXIT=1
 fi
 
+if ! command -v mksquashfs &> /dev/null
+then
+	echo "ERROR: xorriso not found. Run 'apt install squashfs-tools'."
+	EXIT=1
+fi
+
 if ! command -v xorriso &> /dev/null
 then
 	echo "ERROR: xorriso not found. Run 'apt install xorriso'."