diff --git a/autoinstall/build-iso.sh b/autoinstall/build-iso.sh
index 68feab7..7ab0531 100644
--- a/autoinstall/build-iso.sh
+++ b/autoinstall/build-iso.sh
@@ -64,9 +64,11 @@ cp "$GRUB_CFG" "$GRUB_CFG.orig"
 sed -i "s/set timeout=.*/set timeout=5/" "$GRUB_CFG"
 sed -i "s/set timeout_style=.*/set timeout_style=countdown/" "$GRUB_CFG"
 
-# Add autoinstall params to the first linux kernel line
-# Note: semicolon must be backslash-escaped in GRUB or it's treated as command separator
-sed -i "/^\s*linux.*vmlinuz/s/$/ autoinstall ds=nocloud\\;s=\/cdrom\/nocloud\//" "$GRUB_CFG"
+# Add autoinstall params BEFORE the '---' separator on the kernel line.
+# Anything after '---' in a GRUB linux line goes to init, not the kernel.
+# So 'autoinstall' and 'ds=' must be inserted BEFORE '---'.
+# Semicolon is backslash-escaped so GRUB doesn't treat it as a command separator.
+sed -i "/^\s*linux.*vmlinuz/s/---/autoinstall ds=nocloud\\;s=\/cdrom\/nocloud\/ ---/" "$GRUB_CFG"
 echo "✓ GRUB patched"
 
 # ── Extract MBR and EFI partition from original ISO ────