diff --git a/src/Services/FileService.php b/src/Services/FileService.php
index d0c3dbbc..8a0eb3ba 100644
--- a/src/Services/FileService.php
+++ b/src/Services/FileService.php
@@ -112,7 +112,7 @@ class FileService
 			while (!feof($srcHandle))
 			{
 				$buffer = fread($srcHandle, 4 * 1024);
-				if ($maxBytes !== null and ftell($dstHandle) > $maxBytes)
+				if ($maxBytes !== null and strlen($result) > $maxBytes)
 				{
 					throw new \Exception(
 						'File is too big (maximum size: %s)',