diff --git a/src/PhpSpreadsheet/Style/Font.php b/src/PhpSpreadsheet/Style/Font.php
index eee7df04..a062a38f 100644
--- a/src/PhpSpreadsheet/Style/Font.php
+++ b/src/PhpSpreadsheet/Style/Font.php
@@ -357,21 +357,18 @@ class Font extends Supervisor
     /**
      * Set Superscript.
      *
-     * @param bool $pValue
-     *
      * @return $this
      */
-    public function setSuperscript($pValue)
+    public function setSuperscript(bool $pValue)
     {
-        if ($pValue == '') {
-            $pValue = false;
-        }
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['superscript' => $pValue]);
             $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($styleArray);
         } else {
             $this->superscript = $pValue;
-            $this->subscript = !$pValue;
+            if ($this->superscript) {
+                $this->subscript = false;
+            }
         }
 
         return $this;
@@ -394,21 +391,18 @@ class Font extends Supervisor
     /**
      * Set Subscript.
      *
-     * @param bool $pValue
-     *
      * @return $this
      */
-    public function setSubscript($pValue)
+    public function setSubscript(bool $pValue)
     {
-        if ($pValue == '') {
-            $pValue = false;
-        }
         if ($this->isSupervisor) {
             $styleArray = $this->getStyleArray(['subscript' => $pValue]);
             $this->getActiveSheet()->getStyle($this->getSelectedCells())->applyFromArray($styleArray);
         } else {
             $this->subscript = $pValue;
-            $this->superscript = !$pValue;
+            if ($this->subscript) {
+                $this->superscript = false;
+            }
         }
 
         return $this;
diff --git a/tests/PhpSpreadsheetTests/Style/FontTest.php b/tests/PhpSpreadsheetTests/Style/FontTest.php
new file mode 100644
index 00000000..c014a4b6
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Style/FontTest.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Style;
+
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+use PHPUnit\Framework\TestCase;
+
+class FontTest extends TestCase
+{
+    public function testSuperSubScript(): void
+    {
+        $spreadsheet = new Spreadsheet();
+        $sheet = $spreadsheet->getActiveSheet();
+        $cell = $sheet->getCell('A1');
+        $cell->setValue('Cell A1');
+        $font = $cell->getStyle()->getFont();
+        $font->setSuperscript(true);
+        $font->setSubscript(true);
+        self::assertFalse($font->getSuperscript(), 'Earlier set true loses');
+        self::assertTrue($font->getSubscript(), 'Last set true wins');
+        $font->setSubscript(true);
+        $font->setSuperscript(true);
+        self::assertTrue($font->getSuperscript(), 'Last set true wins');
+        self::assertFalse($font->getSubscript(), 'Earlier set true loses');
+        $font->setSuperscript(false);
+        $font->setSubscript(false);
+        self::assertFalse($font->getSuperscript(), 'False remains unchanged');
+        self::assertFalse($font->getSubscript(), 'False remains unchanged');
+        $font->setSubscript(false);
+        $font->setSuperscript(false);
+        self::assertFalse($font->getSuperscript(), 'False remains unchanged');
+        self::assertFalse($font->getSubscript(), 'False remains unchanged');
+        $font->setSubscript(true);
+        $font->setSuperscript(false);
+        self::assertFalse($font->getSuperscript(), 'False remains unchanged');
+        self::assertTrue($font->getSubscript(), 'True remains unchanged');
+        $font->setSubscript(false);
+        $font->setSuperscript(true);
+        self::assertTrue($font->getSuperscript());
+        self::assertFalse($font->getSubscript(), 'False remains unchanged');
+    }
+}