diff --git a/src/alloc.ts b/src/alloc.ts
index ed3d5f9..3e28ebc 100644
--- a/src/alloc.ts
+++ b/src/alloc.ts
@@ -4,23 +4,21 @@ import { asUint8Array } from './util/as-uint8array.js'
  * Returns a `Uint8Array` of the requested size. Referenced memory will
  * be initialized to 0.
  */
-export function alloc (size: number = 0): Uint8Array {
-  if (globalThis.Buffer?.alloc != null) {
-    return asUint8Array(globalThis.Buffer.alloc(size))
+export const alloc = (() => {
+  if (globalThis.Buffer.alloc != null) {
+    return (len: number = 0) => asUint8Array(globalThis.Buffer.alloc(len))
   }
-
-  return new Uint8Array(size)
-}
+  return (len: number = 0) => new Uint8Array(len)
+})()
 
 /**
  * Where possible returns a Uint8Array of the requested size that references
  * uninitialized memory. Only use if you are certain you will immediately
  * overwrite every value in the returned `Uint8Array`.
  */
-export function allocUnsafe (size: number = 0): Uint8Array {
-  if (globalThis.Buffer?.allocUnsafe != null) {
-    return asUint8Array(globalThis.Buffer.allocUnsafe(size))
+export const allocUnsafe = (() => {
+  if (globalThis.Buffer.allocUnsafe != null) {
+    return (len: number = 0) => asUint8Array(globalThis.Buffer.allocUnsafe(len))
   }
-
-  return new Uint8Array(size)
-}
+  return (len: number = 0) => new Uint8Array(len)
+})()
diff --git a/src/concat.ts b/src/concat.ts
index 71ad369..f03f2d0 100644
--- a/src/concat.ts
+++ b/src/concat.ts
@@ -4,22 +4,24 @@ import { asUint8Array } from './util/as-uint8array.js'
 /**
  * Returns a new Uint8Array created by concatenating the passed Uint8Arrays
  */
-export function concat (arrays: Uint8Array[], length?: number): Uint8Array {
-  if (globalThis.Buffer != null) {
-    return asUint8Array(globalThis.Buffer.concat(arrays, length))
-  }
+export const concat = (():((arrays: Uint8Array[], length?: number) => Uint8Array) => globalThis.Buffer != null
+  ? (arrays, length?) => asUint8Array(globalThis.Buffer.concat(arrays, length))
+  : (arrays, length?) => {
+      if (length == null) {
+        length = 0
+        for (const array of arrays) {
+          length += array.length
+        }
+      }
 
-  if (length == null) {
-    length = arrays.reduce((acc, curr) => acc + curr.length, 0)
-  }
+      const output = allocUnsafe(length)
+      let offset = 0
 
-  const output = allocUnsafe(length)
-  let offset = 0
+      for (const arr of arrays) {
+        output.set(arr, offset)
+        offset += arr.length
+      }
 
-  for (const arr of arrays) {
-    output.set(arr, offset)
-    offset += arr.length
-  }
-
-  return asUint8Array(output)
-}
+      return output
+    }
+)()
diff --git a/src/util/as-uint8array.ts b/src/util/as-uint8array.ts
index 9a24af5..a544f85 100644
--- a/src/util/as-uint8array.ts
+++ b/src/util/as-uint8array.ts
@@ -2,10 +2,9 @@
  * To guarantee Uint8Array semantics, convert nodejs Buffers
  * into vanilla Uint8Arrays
  */
-export function asUint8Array (buf: Uint8Array): Uint8Array {
+export const asUint8Array = (() => {
   if (globalThis.Buffer != null) {
-    return new Uint8Array(buf.buffer, buf.byteOffset, buf.byteLength)
+    return (buf: Uint8Array | globalThis.Buffer): Uint8Array => buf.constructor !== Uint8Array ? new Uint8Array(buf.buffer, buf.byteOffset, buf.byteLength) : buf
   }
-
-  return buf
-}
+  return (buf: Uint8Array) => buf
+})()
diff --git a/src/xor.ts b/src/xor.ts
index e53435d..9d77bba 100644
--- a/src/xor.ts
+++ b/src/xor.ts
@@ -1,5 +1,4 @@
 import { allocUnsafe } from './alloc.js'
-import { asUint8Array } from './util/as-uint8array.js'
 
 /**
  * Returns the xor distance between two arrays
@@ -15,5 +14,5 @@ export function xor (a: Uint8Array, b: Uint8Array): Uint8Array {
     result[i] = a[i] ^ b[i]
   }
 
-  return asUint8Array(result)
+  return result
 }