diff --git a/deployment.sh b/deployment.sh
index f602008..7744f74 100755
--- a/deployment.sh
+++ b/deployment.sh
@@ -1389,7 +1389,10 @@ sync
 umount $TARGET || umount -l $TARGET # fall back if a process is still being active
 
 # make sure /etc/fstab is up2date
-blockdev --rereadpt /dev/$DISK || true
+if ! blockdev --rereadpt /dev/$DISK ; then
+  echo "Something on disk /dev/$DISK (mountpoint $TARGET) seems to be still active, debugging output follows:"
+  ps auxwww || true
+fi
 
 # party time! who brings the whiskey?
 echo "Installation finished. \o/"