diff --git a/dll/win32/setupapi/devclass.c b/dll/win32/setupapi/devclass.c
index b8531b0093d..56398262437 100644
--- a/dll/win32/setupapi/devclass.c
+++ b/dll/win32/setupapi/devclass.c
@@ -142,7 +142,7 @@ SETUP_CreateDevicesList(
     {
         cr = CM_Get_Device_ID_List_ExW(Enumerator,
                                        Buffer,
-                                       BufferLength,
+                                       BufferLength / sizeof(WCHAR),
                                        Enumerator ? CM_GETIDLIST_FILTER_ENUMERATOR : CM_GETIDLIST_FILTER_NONE,
                                        list->hMachine);
         if (cr == CR_BUFFER_SMALL)