diff --git a/internal/paramutil/field.go b/internal/paramutil/field.go
index 7bc23f5..48f4e60 100644
--- a/internal/paramutil/field.go
+++ b/internal/paramutil/field.go
@@ -1,6 +1,9 @@
 package paramutil
 
-import "github.com/openai/openai-go/packages/param"
+import (
+	"github.com/openai/openai-go/packages/param"
+	"github.com/openai/openai-go/packages/resp"
+)
 
 func AddrIfPresent[T comparable](v param.Opt[T]) *T {
 	if v.IsPresent() {
@@ -8,3 +11,12 @@ func AddrIfPresent[T comparable](v param.Opt[T]) *T {
 	}
 	return nil
 }
+
+func ToOpt[T comparable](v T, meta resp.Field) param.Opt[T] {
+	if meta.IsPresent() {
+		return param.NewOpt(v)
+	} else if meta.IsExplicitNull() {
+		return param.NullOpt[T]()
+	}
+	return param.Opt[T]{}
+}