diff --git a/src/Smalot/PdfParser/RawData/FilterHelper.php b/src/Smalot/PdfParser/RawData/FilterHelper.php
index a6f11b30..4bab847e 100644
--- a/src/Smalot/PdfParser/RawData/FilterHelper.php
+++ b/src/Smalot/PdfParser/RawData/FilterHelper.php
@@ -282,7 +282,7 @@ protected function decodeFilterLZWDecode(string $data): string
         // convert string to binary string
         $bitstring = '';
         for ($i = 0; $i < $data_length; ++$i) {
-            $bitstring .= sprintf('%08b', \ord($data[$i]));
+            $bitstring .= \sprintf('%08b', \ord($data[$i]));
         }
         // get the number of bits
         $data_length = \strlen($bitstring);