diff --git a/src/PhpSpreadsheet/HashTable.php b/src/PhpSpreadsheet/HashTable.php
index e615b060..445addd6 100644
--- a/src/PhpSpreadsheet/HashTable.php
+++ b/src/PhpSpreadsheet/HashTable.php
@@ -111,7 +111,7 @@ class HashTable
      *
      * @param string $hashCode
      *
-     * @return int Index
+     * @return false|int Index
      */
     public function getIndexForHashCode($hashCode)
     {
diff --git a/src/PhpSpreadsheet/Helper/Size.php b/src/PhpSpreadsheet/Helper/Size.php
index 12bccaad..80b6fbd7 100644
--- a/src/PhpSpreadsheet/Helper/Size.php
+++ b/src/PhpSpreadsheet/Helper/Size.php
@@ -14,7 +14,7 @@ class Size
 
     public function __construct(string $size)
     {
-        $this->valid = preg_match(self::REGEXP_SIZE_VALIDATION, $size, $matches);
+        $this->valid = (bool) preg_match(self::REGEXP_SIZE_VALIDATION, $size, $matches);
         if ($this->valid) {
             $this->size = $matches['size'];
             $this->unit = $matches['unit'] ?? 'pt';