diff --git a/CHANGELOG.md b/CHANGELOG.md
index 74d75470..b62c555f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 - Improve XLSX parsing speed if no readFilter is applied - [#772](https://github.com/PHPOffice/PhpSpreadsheet/issues/772)
 - Fix column names if read filter calls in XLSX reader skip columns - [#777](https://github.com/PHPOffice/PhpSpreadsheet/pull/777)
+- Fix LOOKUP function which was breaking on edge cases - [#796](https://github.com/PHPOffice/PhpSpreadsheet/issues/796)
 
 ## [1.5.2] - 2018-11-25
 
diff --git a/src/PhpSpreadsheet/Calculation/LookupRef.php b/src/PhpSpreadsheet/Calculation/LookupRef.php
index 9a2937fb..92115fff 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef.php
@@ -811,11 +811,13 @@ class LookupRef
         if (!is_array($lookup_vector)) {
             return Functions::NA();
         }
+        $hasResultVector = isset($result_vector);
         $lookupRows = count($lookup_vector);
         $l = array_keys($lookup_vector);
         $l = array_shift($l);
         $lookupColumns = count($lookup_vector[$l]);
-        if ((($lookupRows == 1) && ($lookupColumns > 1)) || (($lookupRows == 2) && ($lookupColumns != 2))) {
+        // we correctly orient our results
+        if (($lookupRows === 1 && $lookupColumns > 1) || (!$hasResultVector && $lookupRows === 2 && $lookupColumns !== 2)) {
             $lookup_vector = self::TRANSPOSE($lookup_vector);
             $lookupRows = count($lookup_vector);
             $l = array_keys($lookup_vector);
@@ -829,18 +831,20 @@ class LookupRef
         $l = array_keys($result_vector);
         $l = array_shift($l);
         $resultColumns = count($result_vector[$l]);
-        if ((($resultRows == 1) && ($resultColumns > 1)) || (($resultRows == 2) && ($resultColumns != 2))) {
+        // we correctly orient our results
+        if ($resultRows === 1 && $resultColumns > 1) {
             $result_vector = self::TRANSPOSE($result_vector);
             $resultRows = count($result_vector);
             $r = array_keys($result_vector);
             $resultColumns = count($result_vector[array_shift($r)]);
         }
 
-        if ($lookupRows == 2) {
+        if ($lookupRows === 2 && !$hasResultVector) {
             $result_vector = array_pop($lookup_vector);
             $lookup_vector = array_shift($lookup_vector);
         }
-        if ($lookupColumns != 2) {
+
+        if ($lookupColumns !== 2) {
             foreach ($lookup_vector as &$value) {
                 if (is_array($value)) {
                     $k = array_keys($value);
diff --git a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
index e7c949fa..acf709be 100644
--- a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
@@ -51,6 +51,22 @@ class LookupRefTest extends TestCase
         return require 'data/Calculation/LookupRef/VLOOKUP.php';
     }
 
+    /**
+     * @dataProvider providerLOOKUP
+     *
+     * @param mixed $expectedResult
+     */
+    public function testLOOKUP($expectedResult, ...$args)
+    {
+        $result = LookupRef::LOOKUP(...$args);
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public function providerLOOKUP()
+    {
+        return require 'data/Calculation/LookupRef/LOOKUP.php';
+    }
+
     /**
      * @dataProvider providerMATCH
      *
diff --git a/tests/data/Calculation/LookupRef/LOOKUP.php b/tests/data/Calculation/LookupRef/LOOKUP.php
new file mode 100644
index 00000000..667d7fd1
--- /dev/null
+++ b/tests/data/Calculation/LookupRef/LOOKUP.php
@@ -0,0 +1,111 @@
+<?php
+return [
+
+    [ // Office reference example #1
+        'orange',
+        4.19,
+        [
+            [4.14],
+            [4.19],
+            [5.17],
+            [5.77],
+            [6,39],
+        ],
+        [
+            ['red'],
+            ['orange'],
+            ['yellow'],
+            ['green'],
+            ['blue'],
+        ],
+    ],
+    [ // Office reference example #2
+        'yellow',
+        5.75,
+        [
+            [4.14],
+            [4.19],
+            [5.17],
+            [5.77],
+            [6,39],
+        ],
+        [
+            ['red'],
+            ['orange'],
+            ['yellow'],
+            ['green'],
+            ['blue'],
+        ],
+    ],
+    [ // Office reference example #3
+        'blue',
+        7.66,
+        [
+            [4.14],
+            [4.19],
+            [5.17],
+            [5.77],
+            [6,39],
+        ],
+        [
+            ['red'],
+            ['orange'],
+            ['yellow'],
+            ['green'],
+            ['blue'],
+        ],
+    ],
+    [ // Office reference example #4
+        '#N/A',
+        0,
+        [
+            [4.14],
+            [4.19],
+            [5.17],
+            [5.77],
+            [6,39],
+        ],
+        [
+            ['red'],
+            ['orange'],
+            ['yellow'],
+            ['green'],
+            ['blue'],
+        ],
+    ],
+
+    [ // Array form test
+        'orange',
+        4.2,
+        [
+            [4.14, 'red'],
+            [4.19, 'orange'],
+            [5.17, 'yellow'],
+            [5.77, 'green'],
+            [6,39, 'blue'],
+        ]
+    ],
+
+    [
+        5,
+        'x',
+        [
+            [0, 0, 0, 'x', 'x'],
+            [1, 2, 3, 4, 5]
+        ]
+    ],
+
+    [
+        'author_100',
+        100,
+        [
+            [100],
+            [101]
+        ],
+        [
+            ['author_100'],
+            ['author_101']
+        ]
+    ]
+
+];