diff --git a/src/byte-helpers.js b/src/byte-helpers.js
index 22d5a6c..80fd5b6 100644
--- a/src/byte-helpers.js
+++ b/src/byte-helpers.js
@@ -35,18 +35,24 @@ export const toUint8 = function(bytes) {
 
 export const toHexString = function(bytes) {
   bytes = toUint8(bytes);
+  let str = '';
 
-  return bytes.reduce(function(acc, b) {
-    return acc + padStart(b.toString(16), 2, '0');
-  }, '');
+  for (let i = 0; i < bytes.length; i++) {
+    str += padStart(bytes[i].toString(16), 2, '0');
+  }
+
+  return str;
 };
 
 export const toBinaryString = function(bytes) {
   bytes = toUint8(bytes);
+  let str = '';
+
+  for (let i = 0; i < bytes.length; i++) {
+    str += padStart(bytes[i].toString(2), 8, '0');
+  }
 
-  return bytes.reduce(function(acc, b) {
-    return acc + padStart(b.toString(2), 8, '0');
-  }, '');
+  return str;
 };
 const BigInt = window.BigInt || Number;
 
diff --git a/src/codec-helpers.js b/src/codec-helpers.js
index 4251191..372869d 100644
--- a/src/codec-helpers.js
+++ b/src/codec-helpers.js
@@ -85,16 +85,18 @@ export const getHvcCodec = function(bytes) {
 
   codec += levelId;
 
-  const constraints = constraintIds.reduce((acc, v) => {
+  let constraints = '';
+
+  for (let i = 0; i < constraintIds.length; i++) {
+    const v = constraintIds[i];
+
     if (v) {
-      if (acc) {
-        acc += '.';
+      if (constraints) {
+        constraints += '.';
       }
-      acc += v.toString(16);
+      constraints += v.toString(16);
     }
-
-    return acc;
-  }, '');
+  }
 
   if (constraints) {
     codec += `.${constraints}`;
diff --git a/test/container.test.js b/test/container.test.js
index da84d30..cf4e2c6 100644
--- a/test/container.test.js
+++ b/test/container.test.js
@@ -71,14 +71,14 @@ const h265seq = toUint8([
   0x00, 0x00, 0x00, 0x01
 ]);
 
-const h264shortnal = Array.prototype.slice.call(testData.h264.slice());
+const h264shortnal = Array.prototype.slice.call(testData.h264);
 
 // remove 0x00 from the front
 h264shortnal.splice(0, 1);
 // remove 0x00 from the back
 h264shortnal.splice(h264shortnal.length - 2, 1);
 
-const h265shortnal = Array.prototype.slice.call(testData.h265.slice());
+const h265shortnal = Array.prototype.slice.call(testData.h265);
 
 // remove 0x00 from the front
 h265shortnal.splice(0, 1);