diff --git a/src/PhpSpreadsheet/Calculation/LookupRef.php b/src/PhpSpreadsheet/Calculation/LookupRef.php
index 9672a6da..8fb2bc6d 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef.php
@@ -627,7 +627,7 @@ class LookupRef
             return Functions::VALUE();
         }
 
-        if (!is_array($arrayValues)) {
+        if (!is_array($arrayValues) || ($rowNum > count($arrayValues))) {
             return Functions::REF();
         }
 
@@ -647,7 +647,7 @@ class LookupRef
                     if (isset($arrayColumn[$rowNum])) {
                         $returnArray[] = $arrayColumn[$rowNum];
                     } else {
-                        return $arrayValues[$rowNum];
+                        return [$rowNum => $arrayValues[$rowNum]];
                     }
                 } else {
                     return $arrayValues[$rowNum];
diff --git a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
index 2671a529..40eb9c73 100644
--- a/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/LookupRefTest.php
@@ -66,4 +66,21 @@ class LookupRefTest extends PHPUnit_Framework_TestCase
     {
         return require 'data/Calculation/LookupRef/MATCH.php';
     }
+
+    /**
+     * @dataProvider providerINDEX
+     * @group fail19
+     *
+     * @param mixed $expectedResult
+     */
+    public function testINDEX($expectedResult, ...$args)
+    {
+        $result = LookupRef::INDEX(...$args);
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public function providerINDEX()
+    {
+        return require 'data/Calculation/LookupRef/INDEX.php';
+    }
 }
diff --git a/tests/data/Calculation/LookupRef/INDEX.php b/tests/data/Calculation/LookupRef/INDEX.php
new file mode 100644
index 00000000..3a9c55a2
--- /dev/null
+++ b/tests/data/Calculation/LookupRef/INDEX.php
@@ -0,0 +1,76 @@
+<?php
+
+return [
+    [
+        [20 => ['R' => 1]], // Expected
+        // Input
+        [20 => ['R' => 1]],
+    ],
+    [
+        '#VALUE!', // Expected
+        // Input
+        [
+            20 => ['R' => 1],
+            21 => ['R' => 2],
+        ],
+        -1,
+    ],
+    [
+        '#REF!', // Expected
+        // Input
+        [
+            20 => ['R' => 1],
+            21 => ['R' => 2],
+        ],
+        10,
+    ],
+    [
+        [21 => ['R' => 2]], // Expected
+        // Input
+        [
+            20 => ['R' => 1],
+            21 => ['R' => 2],
+        ],
+        2,
+    ],
+    [
+        [21 => ['R' => 2, 'S' => 4]], // Expected
+        // Input
+        [
+            '20' => ['R' => 1, 'S' => 3],
+            '21' => ['R' => 2, 'S' => 4],
+        ],
+        2,
+        0,
+    ],
+    [
+        '#VALUE!', // Expected
+        // Input
+        [
+            '20' => ['R' => 1, 'S' => 3],
+            '21' => ['R' => 2, 'S' => 4],
+        ],
+        2,
+        -1,
+    ],
+    [
+        '#VALUE!', // Expected
+        // Input
+        [
+            '20' => ['R' => 1, 'S' => 3],
+            '21' => ['R' => 2, 'S' => 4],
+        ],
+        2,
+        10,
+    ],
+    [
+        4, // Expected
+        // Input
+        [
+            '20' => ['R' => 1, 'S' => 3],
+            '21' => ['R' => 2, 'S' => 4],
+        ],
+        2,
+        2,
+    ],
+];