diff --git a/boa/src/builtins/bigint/operations.rs b/boa/src/builtins/bigint/operations.rs
index 7edbc898c1d..4963d048dc2 100644
--- a/boa/src/builtins/bigint/operations.rs
+++ b/boa/src/builtins/bigint/operations.rs
@@ -4,6 +4,7 @@ use num_traits::cast::ToPrimitive;
 use num_traits::pow::Pow;
 
 use super::BigInt;
+use std::ops::{Neg, Not};
 
 impl BigInt {
     #[inline]
@@ -86,7 +87,7 @@ impl_bigint_operator!(BitAnd, bitand, BitAndAssign, bitand_assign);
 impl_bigint_operator!(BitOr, bitor, BitOrAssign, bitor_assign);
 impl_bigint_operator!(BitXor, bitxor, BitXorAssign, bitxor_assign);
 
-impl std::ops::Neg for BigInt {
+impl Neg for BigInt {
     type Output = Self;
 
     fn neg(self) -> Self::Output {
@@ -94,6 +95,22 @@ impl std::ops::Neg for BigInt {
     }
 }
 
+impl Not for BigInt {
+    type Output = Self;
+
+    fn not(self) -> BigInt {
+        Self(!self.0)
+    }
+}
+
+impl<'a> Not for &'a BigInt {
+    type Output = BigInt;
+
+    fn not(self) -> BigInt {
+        BigInt(!self.clone().0)
+    }
+}
+
 impl std::fmt::Debug for BigInt {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "{}", self.0)
diff --git a/boa/src/syntax/ast/node/operator/unary_op/mod.rs b/boa/src/syntax/ast/node/operator/unary_op/mod.rs
index 30e70d92112..4157d90cf5b 100644
--- a/boa/src/syntax/ast/node/operator/unary_op/mod.rs
+++ b/boa/src/syntax/ast/node/operator/unary_op/mod.rs
@@ -83,18 +83,14 @@ impl Executable for UnaryOp {
             op::UnaryOp::Not => self.target().run(context)?.not(context)?.into(),
             op::UnaryOp::Tilde => {
                 let num_v_a = self.target().run(context)?.to_numeric_number(context)?;
-                if num_v_a.is_nan() {
-                    Value::from(-1)
-                } else if num_v_a.is_infinite() {
-                    Value::from(-1)
+                if num_v_a.is_nan() || num_v_a.is_infinite() {
+                    Value::from(-1) // special case for inf or nan
+                } else if self.target.run(context)?.is_bigint() {
+                    Value::from(!self.target.run(context)?.as_bigint().unwrap())
+                // add bigint support
                 } else {
-                    if self.target.run(context)?.is_bigint() {
-                        Value::from(Value::from(-num_v_a-1f64).to_bigint(context)?)
-                    }
-                    else {
-                        let temp = (num_v_a as i64) & 0x00000000ffffffff;
-                        Value::from(!(temp as i32))
-                    }
+                    let masked = (num_v_a as i64) & 0x00000000ffffffff; // converts float to i32 following spec to ignore MSB using mask
+                    Value::from(!(masked as i32)) // Nots i32 conversion and creates value from this
                 }
             }
             op::UnaryOp::Void => {