diff --git a/examples/main.rs b/examples/main.rs
index 634257e..0a3a833 100644
--- a/examples/main.rs
+++ b/examples/main.rs
@@ -17,6 +17,6 @@ fn main() {
     let n: u64 = 1024;
     let nth_root: u64 = n<<1;
 
-    let ntt_table: Table<'_, u64> = Table::<u64>::new(&mut prime_instance, n, nth_root);
+    let ntt_table: Table<'_, u64> = Table::<u64>::new(&mut prime_instance, nth_root);
 
 }
\ No newline at end of file
diff --git a/src/dft/ntt.rs b/src/dft/ntt.rs
index ae35c27..0bd5886 100644
--- a/src/dft/ntt.rs
+++ b/src/dft/ntt.rs
@@ -5,15 +5,12 @@ pub struct Table<'a, O>{
     prime:&'a Prime<O>,
     pub psi_forward_rev:Vec<Montgomery<O>>,
     psi_backward_rev: Vec<Montgomery<O>>,
-    n_inv: Montgomery<O>,
 }
 
 impl<'a> Table<'a, u64> {
-    pub fn new(prime: &'a mut Prime<u64>, n: u64, nth_root: u64)->Self{
+    pub fn new(prime: &'a mut Prime<u64>, nth_root: u64)->Self{
 
-        assert!(n&(n-1) == 0, "invalid argument: n = {} is not a power of two", n);
-        assert!(n&(n-1) == 0, "invalid argument: nth_root = {} is not a power of two", nth_root);
-        assert!(n < nth_root, "invalid argument: n = {} cannot be greater or equal to nth_root = {}", n, nth_root);
+        assert!(nth_root&(nth_root-1) == 0, "invalid argument: nth_root = {} is not a power of two", nth_root);
 
         let psi: u64 = prime.primitive_nth_root(nth_root);
 
@@ -26,24 +23,21 @@ impl<'a> Table<'a, u64> {
         psi_forward_rev[0] = prime.montgomery.one();
         psi_backward_rev[0] = prime.montgomery.one();
 
-        let log_nth_root_half: usize = (usize::MAX - ((nth_root>>1 as usize)-1).leading_zeros() as usize) as usize;
+        let log_nth_root_half: u32 = usize::BITS - ((nth_root>>1 as usize)-1).leading_zeros();
 
         for i in 1..(nth_root>>1) as usize{
 
-            let i_rev_prev: usize = (i-1).reverse_bits() >> (usize::MAX - log_nth_root_half) as usize;
-            let i_rev_next: usize = i.reverse_bits() >> (usize::MAX - log_nth_root_half) as usize;
+            let i_rev_prev: usize = (i-1).reverse_bits() >> (usize::BITS - log_nth_root_half);
+            let i_rev_next: usize = i.reverse_bits() >> (usize::BITS - log_nth_root_half);
 
             psi_forward_rev[i_rev_next] = prime.montgomery.mul_internal(psi_forward_rev[i_rev_prev], psi_mont);
             psi_backward_rev[i_rev_next] = prime.montgomery.mul_internal(psi_backward_rev[i_rev_prev], psi_inv_mont);
         }
 
-        let n_inv: Montgomery<u64> = prime.montgomery.pow(prime.montgomery.prepare(nth_root>>1), prime.phi-1);
-
         Self{ 
             prime: prime, 
             psi_forward_rev: psi_forward_rev, 
             psi_backward_rev: psi_backward_rev, 
-            n_inv: n_inv,
         }
     }
 }
\ No newline at end of file
diff --git a/src/modulus/barrett.rs b/src/modulus/barrett.rs
index 2a625f3..6b1bfec 100644
--- a/src/modulus/barrett.rs
+++ b/src/modulus/barrett.rs
@@ -25,10 +25,9 @@ impl<O> BarrettPrecomp<O>{
 
 impl BarrettPrecomp<u64>{
     pub fn new(q: u64) -> BarrettPrecomp<u64> {
-        let mut big_r = BigUint::parse_bytes(b"100000000000000000000000000000000", 16).unwrap();
-        big_r = big_r / BigUint::from(q);
-        let lo = (&big_r & BigUint::from(u64::MAX)).to_u64().unwrap();
-        let hi = (big_r >> 64u64).to_u64().unwrap();
+        let big_r: BigUint = (BigUint::from(1 as usize)<<((u64::BITS<<1) as usize)) / BigUint::from(q);
+        let lo: u64 = (&big_r & BigUint::from(u64::MAX)).to_u64().unwrap();
+        let hi: u64 = (big_r >> u64::BITS).to_u64().unwrap();
         Self{q, lo, hi}
     }