diff --git a/wrimg.sh b/wrimg.sh
index 32aa4dd..5c56fb3 100755
--- a/wrimg.sh
+++ b/wrimg.sh
@@ -131,7 +131,7 @@ grow_userdata() {
 wipe_userdata() {
   echo "Zeroing misc..."
   sudo umount $(part_dev 4) 2>/dev/null || true
-  sudo dd if=/dev/zero of=$(part_dev 4) bs=1M
+  sudo dd if=/dev/zero of=$(part_dev 4) bs=1M count=$(( $(sudo blockdev --getsize64 $(part_dev 4)) / 1048576 ))
 
   echo "Creating metadata..."
   sudo umount $(part_dev 8) 2>/dev/null || true