diff --git a/umskt/src/confid/black_box.rs b/umskt/src/confid/black_box.rs
index 294e1e9..e10673b 100644
--- a/umskt/src/confid/black_box.rs
+++ b/umskt/src/confid/black_box.rs
@@ -323,32 +323,29 @@ fn polynomial_mul(
     resultprevdeg
 }
 
-unsafe fn polynomial_div_monic(
+fn polynomial_div_monic(
     adeg: i32,
-    a: *mut u64,
+    a: &mut [u64],
     bdeg: i32,
-    b: *const u64,
-    quotient: *mut u64,
+    b: &[u64],
+    mut quotient: Option<&mut [u64]>,
 ) -> i32 {
     let mut i = adeg - bdeg;
     while i >= 0_i32 {
-        let q: u64 = *a.offset((i + bdeg) as isize);
-        if !quotient.is_null() {
-            *quotient.offset(i as isize) = q;
+        let q: u64 = a[(i + bdeg) as usize];
+        if let Some(ref mut quotient) = quotient {
+            quotient[i as usize] = q;
         }
         let mut j = 0_i32;
         while j < bdeg {
-            *a.offset((i + j) as isize) = residue_sub(
-                *a.offset((i + j) as isize),
-                residue_mul(q, *b.offset(j as isize)),
-            );
+            a[(i + j) as usize] = residue_sub(a[(i + j) as usize], residue_mul(q, b[j as usize]));
             j += 1;
         }
-        *a.offset((i + j) as isize) = 0_i32 as u64;
+        a[(i + j) as usize] = 0_i32 as u64;
         i -= 1;
     }
     i += bdeg;
-    while i >= 0_i32 && *a.offset(i as isize) == 0_i32 as u64 {
+    while i >= 0_i32 && a[i as usize] == 0_i32 as u64 {
         i -= 1;
     }
     i
@@ -603,43 +600,19 @@ unsafe fn divisor_add(src1: *const TDivisor, src2: *const TDivisor, dst: *mut TD
     vdeg = polynomial_mul(c2deg, &c2, tmpdeg, &tmp, vdeg, &mut v);
     if ddeg > 0_i32 {
         let mut udiv: [u64; 5] = [0; 5];
-        polynomial_div_monic(
-            udeg,
-            u.as_mut_ptr(),
-            ddeg,
-            d.as_mut_ptr() as *const u64,
-            udiv.as_mut_ptr(),
-        );
+        polynomial_div_monic(udeg, &mut u, ddeg, &d, Some(&mut udiv));
         udeg -= ddeg;
-        polynomial_div_monic(
-            udeg,
-            udiv.as_mut_ptr(),
-            ddeg,
-            d.as_mut_ptr() as *const u64,
-            u.as_mut_ptr(),
-        );
+        polynomial_div_monic(udeg, &mut udiv, ddeg, &d, Some(&mut u));
         udeg -= ddeg;
         if vdeg >= 0_i32 {
-            polynomial_div_monic(
-                vdeg,
-                v.as_mut_ptr(),
-                ddeg,
-                d.as_mut_ptr() as *const u64,
-                udiv.as_mut_ptr(),
-            );
+            polynomial_div_monic(vdeg, &mut v, ddeg, &d, Some(&mut udiv));
             vdeg -= ddeg;
             for i in 0..=vdeg {
                 v[i as usize] = udiv[i as usize];
             }
         }
     }
-    vdeg = polynomial_div_monic(
-        vdeg,
-        v.as_mut_ptr(),
-        udeg,
-        u.as_mut_ptr() as *const u64,
-        std::ptr::null_mut::<u64>(),
-    );
+    vdeg = polynomial_div_monic(vdeg, &mut v, udeg, &u, None);
     while udeg > 2_i32 {
         // u' = monic((f-v^2)/u), v'=-v mod u'
         tmpdeg = polynomial_mul(vdeg, &v, vdeg, &v, -1_i32, &mut tmp);
@@ -658,13 +631,7 @@ unsafe fn divisor_add(src1: *const TDivisor, src2: *const TDivisor, dst: *mut TD
         }
         tmpdeg = i - 1_i32;
         let mut udiv_0: [u64; 5] = [0; 5];
-        polynomial_div_monic(
-            tmpdeg,
-            tmp.as_mut_ptr(),
-            udeg,
-            u.as_mut_ptr() as *const u64,
-            udiv_0.as_mut_ptr(),
-        );
+        polynomial_div_monic(tmpdeg, &mut tmp, udeg, &u, Some(&mut udiv_0));
         udeg = tmpdeg - udeg;
         let mult: u64 = residue_inv(udiv_0[udeg as usize]);
         i = 0_i32;
@@ -678,13 +645,7 @@ unsafe fn divisor_add(src1: *const TDivisor, src2: *const TDivisor, dst: *mut TD
             v[i as usize] = residue_sub(0_i32 as u64, v[i as usize]);
             i += 1;
         }
-        vdeg = polynomial_div_monic(
-            vdeg,
-            v.as_mut_ptr(),
-            udeg,
-            u.as_mut_ptr() as *const u64,
-            std::ptr::null_mut::<u64>(),
-        );
+        vdeg = polynomial_div_monic(vdeg, &mut v, udeg, &u, None);
     }
     if udeg == 2_i32 {
         (*dst).u[0_i32 as usize] = u[0_i32 as usize];