diff --git a/src/Charts/Chart.php b/src/Charts/Chart.php
index 1a3cf42..a440536 100644
--- a/src/Charts/Chart.php
+++ b/src/Charts/Chart.php
@@ -60,9 +60,11 @@ public function min(float $number, string $axis): self
         return $this;
     }
 
-    public function maintainAspectRatio(bool $enable = true)
+    public function maintainAspectRatio(bool $enable = true): self
     {
         $this->options['maintainAspectRatio'] = $enable;
+
+        return $this;
     }
 
     /**