diff --git a/go/types.cc b/go/types.cc
index fa8c0ad..2fb6706 100644
--- a/go/types.cc
+++ b/go/types.cc
@@ -992,8 +992,10 @@
     return this->btype_;
 
   if (this->named_type() != NULL && this->named_type()->is_alias()) {
-    this->btype_ = this->unalias()->get_backend(gogo);
-    return this->btype_;
+    Btype* bt = this->unalias()->get_backend(gogo);
+    if (gogo != NULL && gogo->named_types_are_converted())
+      this->btype_ = bt;
+    return bt;
   }
 
   if (this->forward_declaration_type() != NULL