diff --git a/nanvm-lib/src/big_numbers/big_uint.rs b/nanvm-lib/src/big_numbers/big_uint.rs
index 3fc5b2fa..a4746208 100644
--- a/nanvm-lib/src/big_numbers/big_uint.rs
+++ b/nanvm-lib/src/big_numbers/big_uint.rs
@@ -249,7 +249,7 @@ impl Mul for &BigUint {
         let mut value = new_resize(total_max + 1);
         let mut i: usize = 0;
         while i < total_max {
-            let mut j = if i > rhs_max { i - rhs_max } else { 0 };
+            let mut j = i.saturating_sub(rhs_max);
             let max = if i < lhs_max { i } else { lhs_max };
             while j <= max {
                 value = add_to_vec(value, i, self.value[j] as u128 * other.value[i - j] as u128);
diff --git a/nanvm-lib/src/js/js_bigint.rs b/nanvm-lib/src/js/js_bigint.rs
index ab1aea98..8d86358c 100644
--- a/nanvm-lib/src/js/js_bigint.rs
+++ b/nanvm-lib/src/js/js_bigint.rs
@@ -184,7 +184,7 @@ fn mul_vec(lhs: &[u64], rhs: &[u64]) -> Vec<u64> {
     let mut vec = new_resize(total_max + 1);
     let mut i: usize = 0;
     while i < total_max {
-        let mut j = if i > rhs_max { i - rhs_max } else { 0 };
+        let mut j = i.saturating_sub(rhs_max);
         let max = if i < lhs_max { i } else { lhs_max };
         while j <= max {
             vec = add_to_vec(vec, i, lhs[j] as u128 * rhs[i - j] as u128);
@@ -378,7 +378,7 @@ pub fn equals(lhs: &JsBigint, rhs: &JsBigint) -> bool {
     if lhs.sign() != rhs.sign() {
         return false;
     }
-    return cmp_vec(lhs.items(), rhs.items()) == Ordering::Equal;
+    cmp_vec(lhs.items(), rhs.items()) == Ordering::Equal
 }
 
 fn to_twos_complement(value: &JsBigint) -> TwosComplement {
diff --git a/nanvm-lib/src/mem/arena.rs b/nanvm-lib/src/mem/arena.rs
index 62ae6964..f2554e4b 100644
--- a/nanvm-lib/src/mem/arena.rs
+++ b/nanvm-lib/src/mem/arena.rs
@@ -34,13 +34,13 @@ impl BlockHeader for NoHeader {
     }
 }
 
-impl<'a> Dealloc for &Arena<'a> {
+impl Dealloc for &Arena<'_> {
     type BlockHeader = NoHeader;
     #[inline(always)]
     unsafe fn dealloc(_: *mut u8, _: Layout) {}
 }
 
-impl<'a> Manager for &Arena<'a> {
+impl Manager for &Arena<'_> {
     type Dealloc = Self;
     unsafe fn alloc(self, layout: Layout) -> *mut u8 {
         let result = {