1 files changed, 4 insertions, 5 deletions
diff --git a/prog/encodingexec.go b/prog/encodingexec.go
index 3b68f6c98..2424a1caa 100644
--- a/prog/encodingexec.go
+++ b/prog/encodingexec.go
@@ -59,6 +59,10 @@ func (p *Prog) SerializeForExec() []byte {
 						}
 						return
 					}
+					if arg1.Kind == ArgUnion {
+						rec(arg1.Option)
+						return
+					}
 					if sys.IsPad(arg1.Type) {
 						return
 					}
@@ -172,11 +176,6 @@ func (w *execContext) writeArg(arg *Arg) {
 			}
 			w.write(v)
 		}
-	case ArgGroup:
-		// Squash groups.
-		for _, arg1 := range arg.Inner {
-			w.writeArg(arg1)
-		}
 	default:
 		panic("unknown arg type")
 	}