diff --git a/tools/widl/write_msft.c b/tools/widl/write_msft.c
index 7904e4539fe..4b09317acfa 100644
--- a/tools/widl/write_msft.c
+++ b/tools/widl/write_msft.c
@@ -885,6 +885,8 @@ static int encode_type(
 
     case VT_VARIANT:
         *encoded_type = default_type;
+        *width = 8 + 2 * pointer_size;
+        *alignment = 8;
         break;
 
     case VT_LPSTR: