diff --git a/Rsconscript b/Rsconscript
index 445a146..1f0b141 100644
--- a/Rsconscript
+++ b/Rsconscript
@@ -8,7 +8,7 @@ class Image < Builder
   def run(options)
     unless @cache.up_to_date?(@target, nil, @sources, @env)
       print_run_message("Image <target>#{@target}<reset>", nil)
-      system(*%W[dd if=/dev/zero of=#{@target} bs=1k count=1440])
+      File.binwrite(@target, "\0" * (1440 * 1024))
       system(*%W[mformat -i #{@target} -f 1440 ::])
       system(*%W[mmd -i #{@target} ::/EFI])
       system(*%W[mmd -i #{@target} ::/EFI/BOOT])