diff --git a/src/SPC/builder/extension/xlswriter.php b/src/SPC/builder/extension/xlswriter.php
index 56b1988c..24d32d94 100644
--- a/src/SPC/builder/extension/xlswriter.php
+++ b/src/SPC/builder/extension/xlswriter.php
@@ -33,7 +33,7 @@ class xlswriter extends Extension
             SourcePatcher::patchFile('spc_fix_xlswriter_win32.patch', $this->source_dir);
             $content = file_get_contents($this->source_dir . '/library/libxlsxwriter/src/theme.c');
             $bom = pack('CCC', 0xEF, 0xBB, 0xBF);
-            if (substr($content, 0, 3) !== $bom) {
+            if (!str_starts_with($content, $bom)) {
                 file_put_contents($this->source_dir . '/library/libxlsxwriter/src/theme.c', $bom . $content);
             }
             return true;