diff --git a/src/DefaultValueBinder.php b/src/DefaultValueBinder.php
index 01346c673..27893981e 100644
--- a/src/DefaultValueBinder.php
+++ b/src/DefaultValueBinder.php
@@ -12,7 +12,7 @@ class DefaultValueBinder extends PhpSpreadsheetDefaultValueBinder
      * @param  mixed  $value  Value to bind in cell
      * @return bool
      */
-    public function bindValue(Cell $cell, $value)
+    public function bindValue(Cell $cell, $value): bool
     {
         if (is_array($value)) {
             $value = \json_encode($value);
diff --git a/src/Filters/ChunkReadFilter.php b/src/Filters/ChunkReadFilter.php
index 4583059f7..a2841d642 100644
--- a/src/Filters/ChunkReadFilter.php
+++ b/src/Filters/ChunkReadFilter.php
@@ -46,7 +46,7 @@ public function __construct(int $headingRow, int $startRow, int $chunkSize, stri
      * @param  string  $worksheetName
      * @return bool
      */
-    public function readCell($column, $row, $worksheetName = '')
+    public function readCell($column, $row, $worksheetName = ''): bool
     {
         //  Only read the heading row, and the rows that are configured in $this->_startRow and $this->_endRow
         return ($worksheetName === $this->worksheetName || $worksheetName === '')
diff --git a/src/Filters/LimitFilter.php b/src/Filters/LimitFilter.php
index 60dc41b3d..694587060 100644
--- a/src/Filters/LimitFilter.php
+++ b/src/Filters/LimitFilter.php
@@ -32,7 +32,7 @@ public function __construct(int $startRow, int $limit)
      * @param  string  $worksheetName
      * @return bool
      */
-    public function readCell($column, $row, $worksheetName = '')
+    public function readCell($column, $row, $worksheetName = ''): bool
     {
         return $row >= $this->startRow && $row < $this->endRow;
     }