diff --git a/src/Upload.php b/src/Upload.php
index 7aef6dd..25b2dbe 100644
--- a/src/Upload.php
+++ b/src/Upload.php
@@ -378,11 +378,11 @@ final class Upload implements JsonSerializable {
             $height = $imagick->getImageHeight();
 
             if ($width > $height) {
-                $resizeWidth = $width * $thumbRes / $height;
+                $resizeWidth = ceil($width * $thumbRes / $height);
                 $resizeHeight = $thumbRes;
             } else {
                 $resizeWidth = $thumbRes;
-                $resizeHeight = $height * $thumbRes / $width;
+                $resizeHeight = ceil($height * $thumbRes / $width);
             }
 
             $imagick->resizeImage(
@@ -393,8 +393,8 @@ final class Upload implements JsonSerializable {
             $imagick->cropImage(
                 $thumbRes,
                 $thumbRes,
-                ($resizeWidth - $thumbRes) / 2,
-                ($resizeHeight - $thumbRes) / 2
+                ceil(($resizeWidth - $thumbRes) / 2),
+                ceil(($resizeHeight - $thumbRes) / 2)
             );
 
             $imagick->writeImage($this->getThumbPath());