diff --git a/reactos/drivers/usb/usbhub/fdo.c b/reactos/drivers/usb/usbhub/fdo.c
index 0e965e3fa01..95b2ad9406c 100644
--- a/reactos/drivers/usb/usbhub/fdo.c
+++ b/reactos/drivers/usb/usbhub/fdo.c
@@ -1035,6 +1035,9 @@ CreateDeviceIds(
         {
             // construct instance id buffer
             Index = swprintf(Buffer, L"%04d&%s", HubDeviceExtension->InstanceCount, SerialBuffer) + 1;
+
+            ExFreePool(SerialBuffer);
+
             UsbChildExtension->usInstanceId.Buffer = (LPWSTR)ExAllocatePool(NonPagedPool, Index * sizeof(WCHAR));
             if (UsbChildExtension->usInstanceId.Buffer == NULL)
             {
@@ -1047,7 +1050,6 @@ CreateDeviceIds(
             //
             RtlCopyMemory(UsbChildExtension->usInstanceId.Buffer, Buffer, Index * sizeof(WCHAR));
             UsbChildExtension->usInstanceId.Length = UsbChildExtension->usInstanceId.MaximumLength = Index * sizeof(WCHAR);
-            ExFreePool(SerialBuffer);
 
             DPRINT("Usb InstanceId %wZ InstanceCount %x\n", &UsbChildExtension->usInstanceId, HubDeviceExtension->InstanceCount);
             return Status;