diff --git a/PHPSkills/Numerics/Matrix.php b/PHPSkills/Numerics/Matrix.php
index 6fb9bad..e3f5ccf 100644
--- a/PHPSkills/Numerics/Matrix.php
+++ b/PHPSkills/Numerics/Matrix.php
@@ -105,7 +105,7 @@ class Matrix
         // I expand along the first row
         for ($currentColumn = 0; $currentColumn < $this->_columnCount; $currentColumn++)
         {
-            $firstRowColValue = $this->_matrixRowValues[0][$currentColumn];
+            $firstRowColValue = $this->_matrixRowData[0][$currentColumn];
             $cofactor = $this->getCofactor(0, $currentColumn);
             $itemToAdd = $firstRowColValue*$cofactor;
             $result = $result + $itemToAdd;
@@ -277,7 +277,7 @@ class Matrix
                     continue;
                 }
 
-                $result[$currentRow][$currentColumn] = $this->_matrixRowData[$currentRow][$currentColumn];
+                $result[$actualRow][$actualCol] = $this->_matrixRowData[$currentRow][$currentColumn];
 
                 $actualCol++;
             }
diff --git a/UnitTests/Numerics/MatrixTest.php b/UnitTests/Numerics/MatrixTest.php
new file mode 100644
index 0000000..19ee9c8
--- /dev/null
+++ b/UnitTests/Numerics/MatrixTest.php
@@ -0,0 +1,101 @@
+<?php
+require_once 'PHPUnit/Framework.php';
+require_once 'PHPUnit/TextUI/TestRunner.php';
+
+require_once(dirname(__FILE__) . '/../../PHPSkills/Numerics/Matrix.php');
+
+use \PHPUnit_Framework_TestCase;
+use Moserware\Numerics\SquareMatrix;
+
+class MatrixTest extends PHPUnit_Framework_TestCase
+{
+    public function testTwoByTwoDeterminant()
+    {
+        $a = new SquareMatrix(1, 2,
+                              3, 4);
+
+        $this->assertEquals(-2, $a->getDeterminant());
+
+        $b = new SquareMatrix(3, 4,
+                              5, 6);
+
+        $this->assertEquals(-2, $b->getDeterminant());
+
+        $c = new SquareMatrix(1, 1,
+                              1, 1);
+
+        $this->assertEquals(0, $c->getDeterminant());
+
+        $d = new SquareMatrix(12, 15,
+                              17, 21);
+
+        $this->assertEquals(12 * 21 - 15 * 17, $d->getDeterminant());
+    }
+
+    public function testThreeByThreeDeterminant()
+    {
+        $a = new SquareMatrix(1, 2, 3,
+                              4, 5, 6,
+                              7, 8, 9);
+        $this->assertEquals(0, $a->getDeterminant());
+
+        $pi = new SquareMatrix(3, 1, 4,
+                               1, 5, 9,
+                               2, 6, 5);
+
+        // Verified against http://www.wolframalpha.com/input/?i=determinant+%7B%7B3%2C1%2C4%7D%2C%7B1%2C5%2C9%7D%2C%7B2%2C6%2C5%7D%7D
+        $this->assertEquals(-90, $pi->getDeterminant());
+    }
+
+    public function testFourByFourDeterminant()
+    {
+        $a = new SquareMatrix( 1,  2,  3,  4,
+                               5,  6,  7,  8,
+                               9, 10, 11, 12,
+                              13, 14, 15, 16);
+
+        $this->assertEquals(0, $a->getDeterminant());
+
+        $pi = new SquareMatrix(3, 1, 4, 1,
+                               5, 9, 2, 6,
+                               5, 3, 5, 8,
+                               9, 7, 9, 3);
+
+        // Verified against http://www.wolframalpha.com/input/?i=determinant+%7B+%7B3%2C1%2C4%2C1%7D%2C+%7B5%2C9%2C2%2C6%7D%2C+%7B5%2C3%2C5%2C8%7D%2C+%7B9%2C7%2C9%2C3%7D%7D
+        $this->assertEquals(98, $pi->getDeterminant());
+    }
+    
+    public function testEightByEightDeterminant()
+    {
+        $a = new SquareMatrix( 1,  2,  3,  4,  5,  6,  7,  8,
+                               9, 10, 11, 12, 13, 14, 15, 16,
+                              17, 18, 19, 20, 21, 22, 23, 24,
+                              25, 26, 27, 28, 29, 30, 31, 32,
+                              33, 34, 35, 36, 37, 38, 39, 40,
+                              41, 42, 32, 44, 45, 46, 47, 48,
+                              49, 50, 51, 52, 53, 54, 55, 56,
+                              57, 58, 59, 60, 61, 62, 63, 64);
+
+        $this->assertEquals(0, $a->getDeterminant());
+
+        $pi = new SquareMatrix(3, 1, 4, 1, 5, 9, 2, 6,
+                               5, 3, 5, 8, 9, 7, 9, 3,
+                               2, 3, 8, 4, 6, 2, 6, 4,
+                               3, 3, 8, 3, 2, 7, 9, 5,
+                               0, 2, 8, 8, 4, 1, 9, 7,
+                               1, 6, 9, 3, 9, 9, 3, 7,
+                               5, 1, 0, 5, 8, 2, 0, 9,
+                               7, 4, 9, 4, 4, 5, 9, 2);
+
+        // Verified against http://www.wolframalpha.com/input/?i=det+%7B%7B3%2C1%2C4%2C1%2C5%2C9%2C2%2C6%7D%2C%7B5%2C3%2C5%2C8%2C9%2C7%2C9%2C3%7D%2C%7B2%2C3%2C8%2C4%2C6%2C2%2C6%2C4%7D%2C%7B3%2C3%2C8%2C3%2C2%2C7%2C9%2C5%7D%2C%7B0%2C2%2C8%2C8%2C4%2C1%2C9%2C7%7D%2C%7B1%2C6%2C9%2C3%2C9%2C9%2C3%2C7%7D%2C%7B5%2C1%2C0%2C5%2C8%2C2%2C0%2C9%7D%2C%7B7%2C4%2C9%2C4%2C4%2C5%2C9%2C2%7D%7D
+        $this->assertEquals(1378143, $pi->getDeterminant());
+    }
+}
+
+$testSuite = new \PHPUnit_Framework_TestSuite();
+$testSuite->addTest( new MatrixTest("testFourByFourDeterminant"));
+$testSuite->addTest( new MatrixTest("testEightByEightDeterminant"));
+
+\PHPUnit_TextUI_TestRunner::run($testSuite);
+
+?>