1 files changed, 1 insertions, 0 deletions

diff --git a/README.md b/README.md
index 2f8c496..4c3cf7b 100644
--- a/README.md
+++ b/README.md
@@ -3,3 +3,4 @@ The kernel name is "work in progress".
 
 # Insights
 * needs on host `apt-get install grub-pc-bin`, otherwise grub-mkrescue makes EFI-only ISO.
+* host needs `mtools`, otherwise grub-mkrescue complains with "`mformat` invocation failed"