diff --git a/src/SPC/builder/extension/xlswriter.php b/src/SPC/builder/extension/xlswriter.php
index 24d32d94..7d0350fc 100644
--- a/src/SPC/builder/extension/xlswriter.php
+++ b/src/SPC/builder/extension/xlswriter.php
@@ -5,6 +5,7 @@ declare(strict_types=1);
 namespace SPC\builder\extension;
 
 use SPC\builder\Extension;
+use SPC\store\FileSystem;
 use SPC\store\SourcePatcher;
 use SPC\util\CustomExt;
 
@@ -28,6 +29,18 @@ class xlswriter extends Extension
     public function patchBeforeMake(): bool
     {
         $patched = parent::patchBeforeMake();
+
+        // Fix K&R C function declaration in bundled minizip rejected by modern Clang (C23 default)
+        $mztools = $this->source_dir . '/library/libxlsxwriter/third_party/minizip/mztools.c';
+        if (file_exists($mztools)) {
+            FileSystem::replaceFileStr(
+                $mztools,
+                "extern int ZEXPORT unzRepair(file, fileOut, fileOutTmp, nRecovered, bytesRecovered)\nconst char* file;\nconst char* fileOut;\nconst char* fileOutTmp;\nuLong* nRecovered;\nuLong* bytesRecovered;\n{",
+                "extern int ZEXPORT unzRepair(const char* file, const char* fileOut, const char* fileOutTmp, uLong* nRecovered, uLong* bytesRecovered)\n{"
+            );
+            $patched = true;
+        }
+
         if (PHP_OS_FAMILY === 'Windows') {
             // fix windows build with openssl extension duplicate symbol bug
             SourcePatcher::patchFile('spc_fix_xlswriter_win32.patch', $this->source_dir);