diff --git a/scripts/daemon/lesavka-core.sh b/scripts/daemon/lesavka-core.sh
index 9be5689..957f17f 100644
--- a/scripts/daemon/lesavka-core.sh
+++ b/scripts/daemon/lesavka-core.sh
@@ -126,9 +126,18 @@ mkdir -p $G/functions/hid.usb0/os_desc
 mkdir -p $G/functions/hid.usb1/os_desc
 mkdir -p $U/os_desc
 
-echo "Lesavka Keyboard"  >$G/functions/hid.usb0/os_desc/interface
-echo "Lesavka Mouse"     >$G/functions/hid.usb1/os_desc/interface
-echo "Lesavka Mic+Spkr"  >$U/os_desc/interface
+# ---------- optional Microsoft OS descriptors ----------------------
+if [ -e "$G/os_desc/use" ]; then
+    echo 1        >"$G/os_desc/use"
+    echo 0xcd     >"$G/os_desc/b_vendor_code"
+    echo "MSFT100" >"$G/os_desc/qw_sign"
+
+    ln -s "$G/configs/c.1" "$G/os_desc"          # creates $G/os_desc/conf
+
+    echo "Lesavka Keyboard" >"$G/functions/hid.usb0/os_desc/interface"
+    echo "Lesavka Mouse"    >"$G/functions/hid.usb1/os_desc/interface"
+    echo "Lesavka Mic+Spkr" >"$U/os_desc/interface"
+fi
 
 #──────────────────────────────────────────────────
 # 4.  Bind gadget