diff --git a/sbin/grub2-sign b/sbin/grub2-sign
index 37778c9..080d169 100644
--- a/sbin/grub2-sign
+++ b/sbin/grub2-sign
@@ -39,10 +39,10 @@ do
     fi
 done
 
-# Shredding passphrase
 
+# Shredding passphrase
 echo "Shredding passphrase..."
-for ( i=0; $i<10; i++ )
+for (( i=0; $i<10; i++ ))
 do
     pp=`cat /dev/urandom | tr -dc 'a-zA-Z0-9-!@#$%^&*()_+~' | fold -w ${#pp} | head -n 1`
 done