diff --git a/CHANGELOG.md b/CHANGELOG.md
index 22b73339..8d73781d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Better auto-detection of CSV separators - [#305](https://github.com/PHPOffice/PhpSpreadsheet/issues/305)
 - Support for shape style ending with `;` - [#304](https://github.com/PHPOffice/PhpSpreadsheet/issues/304)
 - Freeze Panes takes wrong coordinates for XLSX - [#322](https://github.com/PHPOffice/PhpSpreadsheet/issues/322)
+- `COLUMNS` and `ROWS` functions crashed in some cases - [#336](https://github.com/PHPOffice/PhpSpreadsheet/issues/336)
 
 ## [1.0.0] - 2017-12-25
 
diff --git a/src/PhpSpreadsheet/Calculation/Calculation.php b/src/PhpSpreadsheet/Calculation/Calculation.php
index a5d40d01..3d44b4ed 100644
--- a/src/PhpSpreadsheet/Calculation/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation/Calculation.php
@@ -2784,11 +2784,11 @@ class Calculation
     /**
      * Read the dimensions of a matrix, and re-index it with straight numeric keys starting from row 0, column 0.
      *
-     * @param mixed &$matrix matrix operand
+     * @param array &$matrix matrix operand
      *
      * @return int[] An array comprising the number of rows, and number of columns
      */
-    private static function getMatrixDimensions(&$matrix)
+    public static function getMatrixDimensions(array &$matrix)
     {
         $matrixRows = count($matrix);
         $matrixColumns = 0;
diff --git a/src/PhpSpreadsheet/Calculation/LookupRef.php b/src/PhpSpreadsheet/Calculation/LookupRef.php
index 6c1a71a7..029e7ea6 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef.php
@@ -138,7 +138,7 @@ class LookupRef
 
         reset($cellAddress);
         $isMatrix = (is_numeric(key($cellAddress)));
-        list($columns, $rows) = Calculation::_getMatrixDimensions($cellAddress);
+        list($columns, $rows) = Calculation::getMatrixDimensions($cellAddress);
 
         if ($isMatrix) {
             return $rows;
@@ -218,7 +218,7 @@ class LookupRef
 
         reset($cellAddress);
         $isMatrix = (is_numeric(key($cellAddress)));
-        list($columns, $rows) = Calculation::_getMatrixDimensions($cellAddress);
+        list($columns, $rows) = Calculation::getMatrixDimensions($cellAddress);
 
         if ($isMatrix) {
             return $columns;
diff --git a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
index 6881c114..eef15e3a 100644
--- a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
@@ -79,4 +79,36 @@ class LookupRefTest extends TestCase
     {
         return require 'data/Calculation/LookupRef/INDEX.php';
     }
+
+    /**
+     * @dataProvider providerCOLUMNS
+     *
+     * @param mixed $expectedResult
+     */
+    public function testCOLUMNS($expectedResult, ...$args)
+    {
+        $result = LookupRef::COLUMNS(...$args);
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public function providerCOLUMNS()
+    {
+        return require 'data/Calculation/LookupRef/COLUMNS.php';
+    }
+
+    /**
+     * @dataProvider providerROWS
+     *
+     * @param mixed $expectedResult
+     */
+    public function testROWS($expectedResult, ...$args)
+    {
+        $result = LookupRef::ROWS(...$args);
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public function providerROWS()
+    {
+        return require 'data/Calculation/LookupRef/ROWS.php';
+    }
 }
diff --git a/tests/data/Calculation/LookupRef/COLUMNS.php b/tests/data/Calculation/LookupRef/COLUMNS.php
new file mode 100644
index 00000000..3a6a587c
--- /dev/null
+++ b/tests/data/Calculation/LookupRef/COLUMNS.php
@@ -0,0 +1,36 @@
+<?php
+
+return [
+    [
+        1,
+        null,
+    ],
+    [
+        1,
+        '',
+    ],
+    [
+        '#VALUE!',
+        'foo',
+    ],
+    [
+        0,
+        [],
+    ],
+    [
+        1,
+        [1],
+    ],
+    [
+        1,
+        [1, 1],
+    ],
+    [
+        2,
+        [[1, 1]],
+    ],
+    [
+        1,
+        ['a' => [1, 1]],
+    ],
+];
diff --git a/tests/data/Calculation/LookupRef/ROWS.php b/tests/data/Calculation/LookupRef/ROWS.php
new file mode 100644
index 00000000..93808299
--- /dev/null
+++ b/tests/data/Calculation/LookupRef/ROWS.php
@@ -0,0 +1,36 @@
+<?php
+
+return [
+    [
+        1,
+        null,
+    ],
+    [
+        1,
+        '',
+    ],
+    [
+        '#VALUE!',
+        'foo',
+    ],
+    [
+        0,
+        [],
+    ],
+    [
+        1,
+        [1],
+    ],
+    [
+        2,
+        [1, 1],
+    ],
+    [
+        1,
+        [[1, 1]],
+    ],
+    [
+        2,
+        ['a' => [1, 1]],
+    ],
+];