diff --git a/image-setup.md b/image-setup.md
index 16096f2..40526d8 100644
--- a/image-setup.md
+++ b/image-setup.md
@@ -93,6 +93,6 @@ Assuming OS X:
 
 1. `$ diskutil list` to check correct device
 1. `$ diskutil unmountDisk /dev/disk2` to prepare it for imaging
-1. `$ sudo dd bs=1m count=7680 if=/dev/disk2 of=chilipie-kiosk-$TAG.img` (only dump the relevant first ~8 GB, matching the original `ubuntu-mate` image size)
+1. `$ sudo dd bs=1m count=7680 if=/dev/disk2 of=chilipie-kiosk-$TAG.img` (only dump the relevant first ~8 GB, matching the original `ubuntu-mate` image size; takes around 15 minutes)
 1. `$ openssl sha1 chilipie-kiosk-$TAG.img` and include hash in release notes
 1. `$ zip chilipie-kiosk-$TAG.img.zip chilipie-kiosk-$TAG.img`