diff --git a/src/Data/QRMatrix.php b/src/Data/QRMatrix.php
index 56bca706b..59d36ed43 100644
--- a/src/Data/QRMatrix.php
+++ b/src/Data/QRMatrix.php
@@ -483,6 +483,8 @@ class QRMatrix{
 		$this->maskPattern = $maskPattern;
 		$byteCount = count($data);
 		$size      = $this->moduleCount - 1;
+		$mask      = $this->getMask($this->maskPattern);
+
 
 		for($i = $size, $y = $size, $inc = -1, $byteIndex = 0, $bitIndex  = 7; $i > 0; $i -= 2){
 
@@ -501,7 +503,7 @@ class QRMatrix{
 							$v = (($data[$byteIndex] >> $bitIndex) & 1) === 1;
 						}
 
-						if($this->getMask($x, $y, $maskPattern) === 0){
+						if($mask($x, $y) === 0){
 							$v = !$v;
 						}
 
@@ -532,35 +534,32 @@ class QRMatrix{
 	}
 
 	/**
+	 * ISO/IEC 18004:2000 Section 8.8.1
+	 *
 	 * @see \chillerlan\QRCode\QRMatrix::mapData()
 	 *
-	 * @codeCoverageIgnore
 	 * @internal
 	 *
-	 * @param int $x
-	 * @param int $y
 	 * @param int $maskPattern
 	 *
-	 * @return int
+	 * @return \Closure
 	 * @throws \chillerlan\QRCode\Data\QRCodeDataException
 	 */
-	protected function getMask($x, $y, $maskPattern) {
-		$a = $y + $x;
-		$m = $y * $x;
+	protected function getMask($maskPattern){
 
-		// i hate it so much
-		switch($maskPattern){
-			case 0: return $a % 2;
-			case 1: return $y % 2;
-			case 2: return $x % 3;
-			case 3: return $a % 3;
-			case 4: return (floor($y / 2) + floor($x / 3)) % 2;
-			case 5: return $m % 2 + $m % 3;
-			case 6: return ($m % 2 + $m % 3) % 2;
-			case 7: return ($m % 3 + $a % 2) % 2;
+		if((0b111 & $maskPattern) !== $maskPattern){
+			throw new QRCodeDataException('invalid mask pattern'); // @codeCoverageIgnore
 		}
 
-		throw new QRCodeDataException('invalid mask pattern');
+		return [
+			0b000 => function($x, $y){ return ($x + $y) % 2; },
+			0b001 => function($x, $y){ return $x % 2; },
+			0b010 => function($x, $y){ return $y % 3; },
+			0b011 => function($x, $y){ return ($x + $y) % 3; },
+			0b100 => function($x, $y){ return ((int)($x / 2) + (int)($y / 3)) % 2; },
+			0b101 => function($x, $y){ return (($x * $y) % 2) + (($x * $y) % 3); },
+			0b110 => function($x, $y){ return ((($x * $y) % 2) + (($x * $y) % 3)) % 2; },
+			0b111 => function($x, $y){ return ((($x * $y) % 3) + (($x + $y) % 2)) % 2; },
+		][$maskPattern];
 	}
-
 }
diff --git a/tests/QRCodeTest.php b/tests/QRCodeTest.php
index c9430bc8e..996c53b0d 100644
--- a/tests/QRCodeTest.php
+++ b/tests/QRCodeTest.php
@@ -109,7 +109,7 @@ class QRCodeTest extends QRTestAbstract{
 			'outputInterface' => MyCustomOutput::class,
 		]);
 
-		$expected = '000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000011111110111010000101111010000011111110000000010000010111000001101011000001010000010000000010111010101101011000001101011010111010000000010111010110100111110010100111010111010000000010111010000001101011000001101010111010000000010000010100111110010100111110010000010000000011111110101010101010101010101011111110000000000000000010010100111110010100000000000000000011001110000101111010000101111001011110000000000000000111010000101111010000111100010000000001011010100111110010100111110011001010000000010000101111101011000001101011110011110000000000011010100011000001101011000101110100000000011001100001001101011000001101010011010000000010110111110000001101011000001100110100000000010000100100010100111110010100001100100000000011111110111101111010000101111010100110000000011010000111010000101111010000111100100000000010101111111111110010100111110011001000000000010110001110101011000001101011110011010000000001001111100011000001101011000101110010000000011000100110001101011000001101010011100000000001000011001000001101011000001100110000000000011101001011010100111110010100001100000000000010111010001101111010000101111010100110000000011100000001010000101111010000111100000000000000001110110111110010100111110011001000000000000011001011101011000001101011110011100000000011111110101011000001101011001111110110000000000000000110001101011000001101000111100000000011111110001000001101011000011010110000000000010000010101010100111110010101000100100000000010111010111101111010000101111111100110000000010111010011010000101111010001101100010000000010111010000111110010100111100101101100000000010000010101101011000001101001100111100000000011111110101011000001101011000110010110000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000';
+		$expected = '000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000011111110101011110100001011110011111110000000010000010011111001010011111001010000010000000010111010111000001101011000001010111010000000010111010111010110000011010110010111010000000010111010100110101100000110101010111010000000010000010001101011000001101011010000010000000011111110101010101010101010101011111110000000000000000001010011111001010011000000000000000011110010101111010000101111010100111010000000001110001001011110100001011110110010010000000001100010011111001010011111001011110010000000011010000101000001101011000001011001010000000001101011010010110000011010110100000100000000000001001001110101100000110101101011100000000011100010100101011000001101011001100000000000000001000101100101001111100101111101010000000000111011111010111101000010111101100000000000001111000010000101111010000101101001110000000000100011110001111100101001111101000110000000010001001001101100000110101100110100010000000011100111001001101011000001101111011000000000010110101000000011010110000011011101100000000001111011110000110101100000110100001000000000010111100001111110010100111110100110100000000011001011111100001011110100001011010110000000000100101001101000010111101000000100110000000001011011100010100111110010100110011100000000010010101010011010110000011010000010010000000000111011101100000110101100001111110000000000000000000111011000001101011001000110110000000011111110000110000011010110011010111110000000010000010010010011111001010011000111100000000010111010010111010000101111011111101100000000010111010101011110100001011111100010010000000010111010111111001010011111011101010100000000010000010111000001101011000011001101000000000011111110111010110000011010110111100110000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000';
 
 		$this->assertSame($expected, $this->reflection->newInstanceArgs([$options])->render('test'));
 	}