diff --git a/src/PhpSpreadsheet/Calculation/MathTrig.php b/src/PhpSpreadsheet/Calculation/MathTrig.php
index 52cd6c1e..474b2cdd 100644
--- a/src/PhpSpreadsheet/Calculation/MathTrig.php
+++ b/src/PhpSpreadsheet/Calculation/MathTrig.php
@@ -1088,8 +1088,9 @@ class MathTrig
                 list(, $row, $column) = explode('.', $index);
                 if ($cellReference->getWorksheet()->cellExists($column . $row)) {
                     //take this cell out if it contains the SUBTOTAL formula
-                    return !$cellReference->getWorksheet()->getCell($column . $row)->isFormula() &&
-                        !preg_match('/^=.*\bSUBTOTAL\s*\(/', strtoupper($cellReference->getWorksheet()->getCell($column . $row)->getValue()));
+                    $isFormula = $cellReference->getWorksheet()->getCell($column . $row)->isFormula();
+                    $cellFormula = !preg_match('/^=.*\bSUBTOTAL\s*\(/', strtoupper($cellReference->getWorksheet()->getCell($column . $row)->getValue()));
+                    return !$isFormula || $cellFormula;
                 }
                 return true;
             },
diff --git a/tests/PhpSpreadsheetTests/Calculation/MathTrigTest.php b/tests/PhpSpreadsheetTests/Calculation/MathTrigTest.php
index dac660a4..0447ffcb 100644
--- a/tests/PhpSpreadsheetTests/Calculation/MathTrigTest.php
+++ b/tests/PhpSpreadsheetTests/Calculation/MathTrigTest.php
@@ -603,9 +603,13 @@ class MathTrigTest extends TestCase
     }
 
     protected function cellValues($cellValues) {
-        return function() use ($cellValues) {
-            yield from $cellValues;
-        };
+        yield from $cellValues;
+    }
+
+    protected function cellIsFormula($cellValues) {
+        foreach($cellValues as $cellValue) {
+            yield $cellValue[0] === '=';
+        }
     }
 
     /**
@@ -615,18 +619,17 @@ class MathTrigTest extends TestCase
      */
     public function testNestedSUBTOTAL($expectedResult, ...$args)
     {
-        $this->markTestSkipped('Revisite when cellValueGenarator() works for mocking getValue() calls');
-
         $cellValueGenerator = $this->cellValues(Functions::flattenArray(array_slice($args, 1)));
+        $cellIsFormulaGenerator = $this->cellIsFormula(Functions::flattenArray(array_slice($args, 1)));
 
         $cell = $this->getMockBuilder(Cell::class)
             ->setMethods(['getValue', 'isFormula'])
             ->disableOriginalConstructor()
             ->getMock();
         $cell->method('getValue')
-            ->will($this->returnCallback(function() use ($cellValueGenerator) { $result = $cellValueGenerator->current(); $cellValueGenerator->next(); var_dump($result); return $result; }));
+            ->will($this->returnCallback(function() use ($cellValueGenerator) { $result = $cellValueGenerator->current(); $cellValueGenerator->next(); return $result; }));
         $cell->method('isFormula')
-            ->willReturn(true);
+            ->will($this->returnCallback(function() use ($cellIsFormulaGenerator) { $result = $cellIsFormulaGenerator->current(); $cellIsFormulaGenerator->next(); return $result; }));
         $worksheet = $this->getMockBuilder(Worksheet::class)
             ->setMethods(['cellExists', 'getCell'])
             ->disableOriginalConstructor()
@@ -643,6 +646,7 @@ class MathTrigTest extends TestCase
             ->willReturn($worksheet);
 
         array_push($args, $cellReference);
+
         $result = MathTrig::SUBTOTAL(...$args);
         self::assertEquals($expectedResult, $result, null, 1E-12);
     }
@@ -651,5 +655,4 @@ class MathTrigTest extends TestCase
     {
         return require 'data/Calculation/MathTrig/SUBTOTALNESTED.php';
     }
-
 }
diff --git a/tests/data/Calculation/MathTrig/SUBTOTALNESTED.php b/tests/data/Calculation/MathTrig/SUBTOTALNESTED.php
index 564f0f2b..61446cd4 100644
--- a/tests/data/Calculation/MathTrig/SUBTOTALNESTED.php
+++ b/tests/data/Calculation/MathTrig/SUBTOTALNESTED.php
@@ -1,8 +1,8 @@
 <?php
 
 $baseTestData = [
-    1 => ['A' => 1],
-    2 => ['A' => '=2*1'],
+    1 => ['A' => 123],
+    2 => ['A' => 234],
     3 => ['A' => '=SUBTOTAL(1, A1:A2)'],
     4 => ['A' => '=ROMAN(SUBTOTAL(1, A1:A2))'],
     5 => ['A' => 'This is text containing "=" and "SUBTOTAL("'],
@@ -10,8 +10,8 @@ $baseTestData = [
 
 return [
     [
-        2,
-        2,
+        357,
+        9,
         $baseTestData,
     ],
 ];