diff --git a/image-extras/common/root/autoprovision-stage1.sh b/image-extras/common/root/autoprovision-stage1.sh
index 75f1a01..be0c33c 100755
--- a/image-extras/common/root/autoprovision-stage1.sh
+++ b/image-extras/common/root/autoprovision-stage1.sh
@@ -34,7 +34,7 @@ hasBigEnoughPendrive()
 setupPendrivePartitions()
 {
     # erase partition table
-    dd if=/dev/zero of=/dev/sda bs=1M count=1
+    dd if=/dev/zero of=/dev/sda bs=1k count=256
 
     # sda1 is 'swap'
     # sda2 is 'root'