diff --git a/packages/core/src/encoder/Encoder.ts b/packages/core/src/encoder/Encoder.ts
index 61e49156..565b850e 100644
--- a/packages/core/src/encoder/Encoder.ts
+++ b/packages/core/src/encoder/Encoder.ts
@@ -9,12 +9,12 @@ import {
   appendModeInfo,
   appendTerminator,
   calculateBitsNeeded,
-  chooseBestMask,
+  chooseBestMaskAndMatrix,
+  chooseRecommendVersion,
   Hints,
   injectECCodewords,
   isByteMode,
   isHanziMode,
-  recommendVersion,
   Segment,
   SegmentBlock,
   willFit
@@ -23,8 +23,6 @@ import { Encoded } from './Encoded';
 import { Charset } from '/common/Charset';
 import { ECLevel } from '/common/ECLevel';
 import { BitArray } from '/common/BitArray';
-import { buildMatrix } from './utils/matrix';
-import { ByteMatrix } from '/common/ByteMatrix';
 import { Version, VERSIONS } from '/common/Version';
 import { encode as contentEncode, TextEncode } from '/common/encoding';
 import { assertHints, assertLevel, assertVersion } from './utils/asserts';
@@ -106,7 +104,7 @@ export class Encoder {
     let version: Version;
 
     if (versionNumber === 'Auto') {
-      version = recommendVersion(segmentBlocks, ecLevel);
+      version = chooseRecommendVersion(segmentBlocks, ecLevel);
     } else {
       version = VERSIONS[versionNumber - 1];
 
@@ -131,11 +129,8 @@ export class Encoder {
 
     appendTerminator(headAndDataBits, ecBlocks.numTotalDataCodewords);
 
-    const matrix = new ByteMatrix(version.size);
     const codewords = injectECCodewords(headAndDataBits, ecBlocks);
-    const mask = chooseBestMask(matrix, codewords, version, ecLevel);
-
-    buildMatrix(matrix, codewords, version, ecLevel, mask);
+    const [mask, matrix] = chooseBestMaskAndMatrix(codewords, version, ecLevel);
 
     return new Encoded(matrix, version, ecLevel, mask);
   }
diff --git a/packages/core/src/encoder/utils/encoder.ts b/packages/core/src/encoder/utils/encoder.ts
index 81e6cd2c..d57feb1d 100644
--- a/packages/core/src/encoder/utils/encoder.ts
+++ b/packages/core/src/encoder/utils/encoder.ts
@@ -210,7 +210,7 @@ export function calculateBitsNeeded(segmentBlocks: SegmentBlock[], version: Vers
   return bitsNeeded;
 }
 
-export function recommendVersion(segmentBlocks: SegmentBlock[], ecLevel: ECLevel): Version {
+export function chooseRecommendVersion(segmentBlocks: SegmentBlock[], ecLevel: ECLevel): Version {
   // Hard part: need to know version to know how many bits length takes. But need to know how many
   // bits it takes to know version. First we take a guess at version by assuming version will be
   // the minimum, 1:
@@ -222,22 +222,27 @@ export function recommendVersion(segmentBlocks: SegmentBlock[], ecLevel: ECLevel
   return chooseVersion(bitsNeeded, ecLevel);
 }
 
-export function chooseBestMask(matrix: ByteMatrix, bits: BitArray, version: Version, ecLevel: ECLevel): number {
-  let bestMask = -1;
-  // Lower penalty is better.
-  let minPenalty = Number.MAX_VALUE;
-
-  // We try all mask patterns to choose the best one.
-  for (let mask = 0; mask < 8; mask++) {
-    buildMatrix(matrix, bits, version, ecLevel, mask);
+export function chooseBestMaskAndMatrix(
+  bits: BitArray,
+  version: Version,
+  ecLevel: ECLevel
+): [mask: number, matrix: ByteMatrix] {
+  let bestMask = 0;
+  let bestMatrix = buildMatrix(bits, version, ecLevel, bestMask);
+  let minPenalty = calculateMaskPenalty(bestMatrix);
 
+  // We try all rest mask patterns to choose the best one.
+  for (let mask = 1; mask < 8; mask++) {
+    const matrix = buildMatrix(bits, version, ecLevel, mask);
     const penalty = calculateMaskPenalty(matrix);
 
+    // Lower penalty is better.
     if (penalty < minPenalty) {
       bestMask = mask;
+      bestMatrix = matrix;
       minPenalty = penalty;
     }
   }
 
-  return bestMask;
+  return [bestMask, bestMatrix];
 }
diff --git a/packages/core/src/encoder/utils/matrix.ts b/packages/core/src/encoder/utils/matrix.ts
index b03f7281..b02d4258 100644
--- a/packages/core/src/encoder/utils/matrix.ts
+++ b/packages/core/src/encoder/utils/matrix.ts
@@ -339,7 +339,9 @@ function embedEncodingRegion(matrix: ByteMatrix, codewords: BitArray, version: V
 
 // Build 2D matrix of QR Code from "codewords" with "ecLevel", "version" and "getMaskPattern". On
 // success, store the result in "matrix".
-export function buildMatrix(matrix: ByteMatrix, codewords: BitArray, version: Version, ecLevel: ECLevel, mask: number): void {
+export function buildMatrix(codewords: BitArray, version: Version, ecLevel: ECLevel, mask: number): ByteMatrix {
+  const matrix = new ByteMatrix(version.size);
+
   // Clear matrix
   matrix.clear(-1);
 
@@ -347,4 +349,6 @@ export function buildMatrix(matrix: ByteMatrix, codewords: BitArray, version: Ve
   embedFunctionPatterns(matrix, version);
   // Embed encoding region
   embedEncodingRegion(matrix, codewords, version, ecLevel, mask);
+
+  return matrix;
 }