diff --git a/querybuilder/marshal.go b/querybuilder/marshal.go
index df013e5f8..2598bb1ed 100644
--- a/querybuilder/marshal.go
+++ b/querybuilder/marshal.go
@@ -66,7 +66,7 @@ func marshalValue(ctx context.Context, v reflect.Value) (string, error) {
 		var buf bytes.Buffer
 		gqlgen.MarshalString(v.String()).MarshalGQL(&buf)
 		return buf.String(), nil //nolint:gosimple,staticcheck
-	case reflect.Pointer:
+	case reflect.Pointer, reflect.Interface:
 		if v.IsNil() {
 			return "null", nil
 		}
diff --git a/querybuilder/querybuilder.go b/querybuilder/querybuilder.go
index 037bd98a5..c2841e513 100644
--- a/querybuilder/querybuilder.go
+++ b/querybuilder/querybuilder.go
@@ -168,15 +168,16 @@ func (s *Selection) Execute(ctx context.Context, c graphql.Client) error {
 }
 
 type argument struct {
-	value      any
-	marshalled string
-	once       sync.Once
+	value any
+
+	marshalled    string
+	marshalledErr error
+	once          sync.Once
 }
 
 func (a *argument) marshal(ctx context.Context) error {
-	var err error
 	a.once.Do(func() {
-		a.marshalled, err = MarshalGQL(ctx, a.value)
+		a.marshalled, a.marshalledErr = MarshalGQL(ctx, a.value)
 	})
-	return err
+	return a.marshalledErr
 }