diff --git a/polyfill.js b/polyfill.js
index 0829ffd..d5bf378 100644
--- a/polyfill.js
+++ b/polyfill.js
@@ -129,6 +129,27 @@
         }
     }
 
+    /**
+     * @param {TypedArray} example
+     * @param {unknown} value
+     * @description convert `value` to bigint or number based on the the type of array
+     * @returns {bigint | number}
+     * @throws if one of the override methods throws. e.g. `@@toPrimitive`, `valueOf`, `toString`
+     */
+    function typedArrayNumberConversion(example, value) {
+        let asNumber;
+        {
+            if (isBigIntArray(example)) {
+                asNumber = 0n;
+            } else {
+                asNumber = -0; // important to use `-0` and not `0`
+            }
+            // @ts-ignore : using `+=` to emulate ToBigInt or ToNumber
+            asNumber += value;
+        }
+        return asNumber;
+    }
+
     defineArrayMethods({
         toReversed() {
             const o = toObject(this);
@@ -239,8 +260,11 @@
             const o = assertTypedArray(this);
             const len = typedArrayLength(o);
             const { actualStart, actualDeleteCount, newLen } = calculateSplice({ start, deleteCount, len, values, argsCount: arguments.length });
+            const convertedValues = values.map(v => {
+                return typedArrayNumberConversion(o, v);
+            })
             const a = typedArrayCreate(o, newLen);
-            doSplice({ src: o, target: a, actualStart, actualDeleteCount, values, newLen });
+            doSplice({ src: o, target: a, actualStart, actualDeleteCount, values: convertedValues, newLen });
             return a;
         }
     });
@@ -269,16 +293,7 @@
             const len = typedArrayLength(o);
             const relativeIndex = toIntegerOrInfinity(index);
             const actualIndex = relativeIndex < 0 ? len + relativeIndex : relativeIndex;
-            let asNumber;
-            {
-                if (isBigIntArray(o)) {
-                    asNumber = 0n;
-                } else {
-                    asNumber = -0; // important to use `-0` and not `0`
-                }
-                // @ts-ignore : using `+=` to emulate ToBigInt or ToNumber
-                asNumber += value;
-            }
+            const asNumber = typedArrayNumberConversion(o, value);
             if (actualIndex < 0 || actualIndex >= len) {
                 throw new RangeError();
             }
diff --git a/polyfill.test.js b/polyfill.test.js
index 55e79f1..5b3ab84 100644
--- a/polyfill.test.js
+++ b/polyfill.test.js
@@ -219,6 +219,34 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
+    tape(`${TypedArray.name}.prototype.toSpliced performs type conversion early`, (t) => {
+        const orig = new TypedArray([1]);
+        const valueUserCodeWillInsert = 4;
+        const userCodeReturnValue = 5;
+        const expected = new TypedArray([valueUserCodeWillInsert, userCodeReturnValue]);
+
+        let userCodeExecuted = false;
+        /** @type any */
+        const val = {
+            valueOf() {
+                userCodeExecuted = true;
+                orig[0] = valueUserCodeWillInsert;
+                return userCodeReturnValue;
+            }
+        };
+
+        const idx = 1;
+        const delNum = 0;
+        const ins = [val];
+
+        const copy = orig.toSpliced(idx, delNum, ...ins);
+
+        t.deepEqual(copy, expected);
+        t.notEqual(orig, copy);
+        t.notDeepEqual(orig, copy);
+        t.end();
+    });
+
     tape(`${TypedArray.name}.prototype.with`, (t) => {
         const orig = new TypedArray([1, 1, 3]);
         const expected = new TypedArray([1, 2, 3]);
@@ -306,10 +334,10 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
 [
     BigInt64Array,
     BigUint64Array
-].forEach((TypedArray) => {
-    tape(`${TypedArray.name}.prototype.toReversed`, (t) => {
-        const orig = new TypedArray([3n, 2n, 1n]);
-        const expected = new TypedArray([1n, 2n, 3n]);
+].forEach((BigIntArray) => {
+    tape(`${BigIntArray.name}.prototype.toReversed`, (t) => {
+        const orig = new BigIntArray([3n, 2n, 1n]);
+        const expected = new BigIntArray([1n, 2n, 3n]);
 
         const copy = orig.toReversed();
 
@@ -319,9 +347,9 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.toSorted`, (t) => {
-        const orig = new TypedArray([3n, 1n, 2n]);
-        const expected = new TypedArray([1n, 2n, 3n]);
+    tape(`${BigIntArray.name}.prototype.toSorted`, (t) => {
+        const orig = new BigIntArray([3n, 1n, 2n]);
+        const expected = new BigIntArray([1n, 2n, 3n]);
 
         const copy = orig.toSorted();
 
@@ -331,9 +359,9 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.toSorted(compareFn)`, (t) => {
-        const orig = new TypedArray([3n, 1n, 2n]);
-        const expected = new TypedArray([3n, 2n, 1n]);
+    tape(`${BigIntArray.name}.prototype.toSorted(compareFn)`, (t) => {
+        const orig = new BigIntArray([3n, 1n, 2n]);
+        const expected = new BigIntArray([3n, 2n, 1n]);
         function compareFn(a, b) {
             return a > b ? -1 : 1;
         }
@@ -346,9 +374,9 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.toSpliced`, (t) => {
-        const orig = new TypedArray([1n, -1n, 0n, -1n, 4n]);
-        const expected = new TypedArray([1n, 2n, 3n, 4n]);
+    tape(`${BigIntArray.name}.prototype.toSpliced`, (t) => {
+        const orig = new BigIntArray([1n, -1n, 0n, -1n, 4n]);
+        const expected = new BigIntArray([1n, 2n, 3n, 4n]);
         const idx = 1;
         const delNum = 3;
         const ins = [2n, 3n];
@@ -361,9 +389,37 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.with`, (t) => {
-        const orig = new TypedArray([1n, 1n, 3n]);
-        const expected = new TypedArray([1n, 2n, 3n]);
+    tape(`${BigIntArray.name}.prototype.toSpliced performs type conversion early`, (t) => {
+        const orig = new BigIntArray([1n]);
+        const valueUserCodeWillInsert = 4n;
+        const userCodeReturnValue = 5n;
+        const expected = new BigIntArray([valueUserCodeWillInsert, userCodeReturnValue]);
+
+        let userCodeExecuted = false;
+        /** @type any */
+        const val = {
+            valueOf() {
+                userCodeExecuted = true;
+                orig[0] = valueUserCodeWillInsert;
+                return userCodeReturnValue;
+            }
+        };
+
+        const idx = 1;
+        const delNum = 0;
+        const ins = [val];
+
+        const copy = orig.toSpliced(idx, delNum, ...ins);
+
+        t.deepEqual(copy, expected);
+        t.notEqual(orig, copy);
+        t.notDeepEqual(orig, copy);
+        t.end();
+    });
+
+    tape(`${BigIntArray.name}.prototype.with`, (t) => {
+        const orig = new BigIntArray([1n, 1n, 3n]);
+        const expected = new BigIntArray([1n, 2n, 3n]);
         const idx = 1;
         const val = 2n;
 
@@ -375,8 +431,8 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.with non bigint throws`, (t) => {
-        const orig = new TypedArray([1n, 2n, 2n]);
+    tape(`${BigIntArray.name}.prototype.with non bigint throws`, (t) => {
+        const orig = new BigIntArray([1n, 2n, 2n]);
         const idx = 3;
         const val = 4;
 
@@ -388,9 +444,9 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.with negativeIndex`, (t) => {
-        const orig = new TypedArray([1n, 2n, 2n]);
-        const expected = new TypedArray([1n, 2n, 3n]);
+    tape(`${BigIntArray.name}.prototype.with negativeIndex`, (t) => {
+        const orig = new BigIntArray([1n, 2n, 2n]);
+        const expected = new BigIntArray([1n, 2n, 3n]);
         const idx = -1;
         const val = 3n;
 
@@ -402,8 +458,8 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.with out of bounds`, (t) => {
-        const orig = new TypedArray([1n, 2n, 2n]);
+    tape(`${BigIntArray.name}.prototype.with out of bounds`, (t) => {
+        const orig = new BigIntArray([1n, 2n, 2n]);
         const idx = 3;
         const val = 4n;
 
@@ -414,12 +470,12 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name}.prototype.with executes 'user code' before starting copy`, (t) => {
-        const orig = new TypedArray([1n, 2n, 3n]);
+    tape(`${BigIntArray.name}.prototype.with executes 'user code' before starting copy`, (t) => {
+        const orig = new BigIntArray([1n, 2n, 3n]);
         const idx = 1;
         const valueUserCodeWillInsert = 4n;
         const userCodeReturnValue = 5n;
-        const expected = new TypedArray([valueUserCodeWillInsert, userCodeReturnValue, 3n]);
+        const expected = new BigIntArray([valueUserCodeWillInsert, userCodeReturnValue, 3n]);
         let userCodeExecuted = false;
         /** @type any */
         const val = {
@@ -437,12 +493,12 @@ tape("Array.prototype[Symbol.unscopables]", (t) => {
         t.end();
     });
 
-    tape(`${TypedArray.name} does not use Symbol.species for the new methods`, (t) => {
-        class SubClass extends TypedArray { }
+    tape(`${BigIntArray.name} does not use Symbol.species for the new methods`, (t) => {
+        class SubClass extends BigIntArray { }
 
         function assertType(arr) {
             t.equal(arr instanceof SubClass, false);
-            t.equal(arr instanceof TypedArray, true);
+            t.equal(arr instanceof BigIntArray, true);
         }
 
         /** @type {BigInt64Array} */
diff --git a/spec.html b/spec.html
index 4a12d9e..d693007 100644
--- a/spec.html
+++ b/spec.html
@@ -425,6 +425,11 @@ <h1>%TypedArray%.prototype.toSpliced ( _start_, _deleteCount_, ..._items_ )</h1>
                         1. Else if _relativeStart_ &lt; 0, let _actualStart_ be max(_len_ + _relativeStart_, 0).
                         1. Else, let _actualStart_ be min(_relativeStart_, _len_).
                         1. Let _insertCount_ be the number of elements in _items_.
+                        1. Let _convertedItems_ be a new empty List.
+                        1. For each element _E_ of _items_, do
+                            1. If _O_.[[ContentType]] is ~BigInt~, let _convertedValue_ be ? ToBigInt(_E_).
+                            1. Else, let _convertedValue_ be ? ToNumber(_E_).
+                            1. Append _convertedValue_ as the last element of _convertedItems_.
                         1. If _start_ is not present, then
                             1. Let _actualDeleteCount_ be 0.
                         1. Else if _deleteCount_ is not present, then
@@ -441,9 +446,9 @@ <h1>%TypedArray%.prototype.toSpliced ( _start_, _deleteCount_, ..._items_ )</h1>
                             1. Let _iValue_ be ! Get(_src_, _Pi_).
                             1. Perform ! Set(_target_, _Pi_, _iValue_, *true*).
                             1. Set _i_ to _i_ + 1.
-                        1. For each element _E_ of _items_, do
+                        1. For each element _E_ of _convertedItems_, do
                             1. Let _Pi_ be ! ToString(𝔽(_i_)).
-                            1. [id="step-typedarray-tospliced-set"] Perform ? Set(_A_, _Pi_, _E_, *true*).
+                            1. Perform ! Set(_A_, _Pi_, _E_, *true*).
                             1. Set _i_ to _i_ + 1.
                         1. Repeat, while _r_ &lt; _newLen_,
                             1. Let _Pi_ be ! ToString(𝔽(_i_)).
@@ -454,9 +459,6 @@ <h1>%TypedArray%.prototype.toSpliced ( _start_, _deleteCount_, ..._items_ )</h1>
                             1. Set _r_ to _r_ + 1.
                         1. Return _A_.
                     </emu-alg>
-                    <emu-note>
-                        Step <emu-xref href="#step-typedarray-tospliced-set"></emu-xref> may return an abrupt completion because _E_ is a value of any ECMAScript language type and is passed to ToBigInt or ToNumber.
-                    </emu-note>
                 </emu-clause>
 
                 <emu-clause id="sec-%typedarray%.prototype.with">