diff --git a/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php b/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
index d578854de..228b46448 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
@@ -81,7 +81,6 @@ class Matrix
         }
 
         $rowNum = $rowNum ?? 0;
-        $originalColumnNum = $columnNum;
         $columnNum = $columnNum ?? 0;
 
         try {
@@ -91,6 +90,17 @@ class Matrix
             return $e->getMessage();
         }
 
+        if (is_array($matrix) && count($matrix) === 1 && $rowNum > 1) {
+            $matrixKey = array_keys($matrix)[0];
+            if (is_array($matrix[$matrixKey])) {
+                $tempMatrix = [];
+                foreach ($matrix[$matrixKey] as $key => $value) {
+                    $tempMatrix[$key] = [$value];
+                }
+                $matrix = $tempMatrix;
+            }
+        }
+
         if (!is_array($matrix) || ($rowNum > count($matrix))) {
             return ExcelError::REF();
         }
@@ -101,9 +111,6 @@ class Matrix
         if ($columnNum > count($columnKeys)) {
             return ExcelError::REF();
         }
-        if ($originalColumnNum === null && 1 < count($columnKeys)) {
-            return ExcelError::REF();
-        }
 
         if ($columnNum === 0) {
             return self::extractRowValue($matrix, $rowKeys, $rowNum);
diff --git a/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/IndexOnSpreadsheetTest.php b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/IndexOnSpreadsheetTest.php
index e893fc7f3..3f508405a 100644
--- a/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/IndexOnSpreadsheetTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/IndexOnSpreadsheetTest.php
@@ -34,4 +34,37 @@ class IndexOnSpreadsheetTest extends AllSetupTeardown
     {
         return require 'tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php';
     }
+
+    /**
+     * @dataProvider providerIndexLiteralArrays
+     */
+    public function testLiteralArrays(mixed $expectedResult, string $indexArgs): void
+    {
+        $sheet = $this->getSheet();
+        $sheet->getCell('A10')->setValue(10);
+        $sheet->getCell('B10')->setValue(11);
+        $sheet->getCell('C10')->setValue(12);
+        $sheet->getCell('D10')->setValue(13);
+        $sheet->getCell('X10')->setValue(10);
+        $sheet->getCell('X11')->setValue(11);
+        $sheet->getCell('X12')->setValue(12);
+        $sheet->getCell('X13')->setValue(13);
+        $sheet->getCell('A1')->setValue("=INDEX($indexArgs)");
+        $result = $sheet->getCell('A1')->getCalculatedValue();
+        self::assertEquals($expectedResult, $result);
+    }
+
+    public static function providerIndexLiteralArrays(): array
+    {
+        return [
+            'issue 64' => ['Fourth', '{"First","Second","Third","Fourth","Fifth","Sixth","Seventh"}, 4'],
+            'issue 64 selecting first "row"' => ['First', '{"First","Second","Third","Fourth","Fifth","Sixth","Seventh"}, 1'],
+            'array result condensed to single value' => [40, '{10,11;20,21;30,31;40,41;50,51;60,61},4'],
+            'both row and column' => [41, '{10,11;20,21;30,31;40,41;50,51;60,61},4,2'],
+            '1*1 array' => ['first', '{"first"},1'],
+            'array expressed in rows' => [20, '{10;20;30;40},2'],
+            'spreadsheet single row' => [11, 'A10:D10,2'],
+            'spreadsheet single column' => [13, 'X10:X13,4'],
+        ];
+    }
 }
diff --git a/tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php b/tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php
index 76f6ddd46..b2202704d 100644
--- a/tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php
+++ b/tests/data/Calculation/LookupRef/INDEXonSpreadsheet.php
@@ -82,7 +82,7 @@ return [
         2,
     ],
     'Column number omitted from 2-column matrix' => [
-        '#REF!', // Expected
+        'abc', // Expected
         [
             ['abc', 'def'],
             ['xyz', 'tuv'],