diff --git a/inc_vars.php b/inc_vars.php
index 4e7d87ce9bd2a3695f5b27533b6ef8ebc45a1d73..94f9724d6823e1e01e97ac0ed1964743de419c53 100644
--- a/inc_vars.php
+++ b/inc_vars.php
@@ -1,16 +1,40 @@
 <?php
 
+$selfdir=dirname(__FILE__);
+$dirExternal="external";
+$dirBuild="build";
+$dirPackages="built_packages";
+
+// ---------- build with spc
+
+// php version for spc
 $php_version="8.3";
 
 // extensions - see https://static-php.dev/en/guide/extensions.html
 $php_libs="mysqli,openssl,pdo,pdo_mysql,pdo_pgsql,pdo_sqlite,sockets";
 
-$myos=strtolower(PHP_OS);
+// TODO: how can it be dynamic?
 $myarchitecture="x86_64";
+// $myarchitecture="aarch64";
 
-$selfdir=dirname(__FILE__);
-$dirExternal="external";
-$dirBuild="build";
-$dirPackages="built_packages";
+$myos=strtolower(PHP_OS);
+
+// TODO: check value on MS Windows
+switch ($myos) {
+    case 'cygwin_nt-5.1':
+    case 'windows':
+    case 'winnt':
+        $myos="windows";
+        $myarchitecture="x64";
+        break;
+    case 'win32':
+        $myos="win";
+        $myarchitecture="i386";
+        break;
+    case 'darwin':
+        $myos="macos";
+        break;
+}
+$myosextension=$myos=="Win" ? ".exe" : "";
 
-$SPC="$selfdir/$dirExternal/bin/spc";
+$SPC="$selfdir/$dirExternal/bin/spc$myosextension";