diff --git a/chronos/internal/raisesfutures.nim b/chronos/internal/raisesfutures.nim
index 5b91f41..ed85c03 100644
--- a/chronos/internal/raisesfutures.nim
+++ b/chronos/internal/raisesfutures.nim
@@ -142,7 +142,7 @@ macro union*(tup0: typedesc, tup1: typedesc): typedesc =
     if not found:
       result.add err
 
-  for err2 in getType(getTypeInst(tup1)[1])[1..^1]:
+  for err2 in tup1.members():
     result.add err2
   if result.len == 0:
     result = makeNoRaises()