diff --git a/bin/check-disk-usage.rb b/bin/check-disk-usage.rb
index 773ec21..c793985 100755
--- a/bin/check-disk-usage.rb
+++ b/bin/check-disk-usage.rb
@@ -215,7 +215,7 @@ def percent_bytes(fs_info)
       if nonroot_total.zero?
         0
       else
-        ('%.2f' % (u100 / nonroot_total + (u100 % nonroot_total != 0 ? 1 : 0))).to_f
+        (u100 / nonroot_total + (u100 % nonroot_total != 0 ? 1 : 0)).round(2)
       end
     else
       (100.0 - (100.0 * fs_info.bytes_free / fs_info.bytes_total)).round(2)