diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index 0fc7e4f38c..07d4363f89 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -618,7 +618,7 @@ func (w *writer) objDict(obj types2.Object, dict *writerDict) {
 	ntparams := tparams.Len()
 	w.len(ntparams)
 	for i := 0; i < ntparams; i++ {
-		w.typ(tparams.At(i).Type().(*types2.TypeParam).Bound())
+		w.typ(tparams.At(i).Type().(*types2.TypeParam).Constraint())
 	}
 
 	nderived := len(dict.derived)