diff --git a/cmd/protoc-gen-go-vtproto/main.go b/cmd/protoc-gen-go-vtproto/main.go
index 0f0016e..6f9209e 100644
--- a/cmd/protoc-gen-go-vtproto/main.go
+++ b/cmd/protoc-gen-go-vtproto/main.go
@@ -19,9 +19,10 @@ import (
 func main() {
 	var cfg generator.Config
 	var features string
-
 	var f flag.FlagSet
+
 	f.BoolVar(&cfg.AllowEmpty, "allow-empty", false, "allow generation of empty files")
+	cfg.Poolable = make(generator.ObjectSet)
 	f.Var(&cfg.Poolable, "pool", "use memory pooling for this object")
 	f.BoolVar(&cfg.Wrap, "wrap", false, "generate wrapper types")
 	f.BoolVar(&cfg.WellKnownTypes, "wkt", true, "generate optimized code for well-known types")
diff --git a/generator/generator.go b/generator/generator.go
index 3e520d4..d3afaa2 100644
--- a/generator/generator.go
+++ b/generator/generator.go
@@ -22,11 +22,11 @@ type featureHelpers struct {
 
 type ObjectSet map[protogen.GoIdent]bool
 
-func (o *ObjectSet) String() string {
-	return fmt.Sprintf("%#v", *o)
+func (o ObjectSet) String() string {
+	return fmt.Sprintf("%#v", o)
 }
 
-func (o *ObjectSet) Set(s string) error {
+func (o ObjectSet) Set(s string) error {
 	idx := strings.LastIndexByte(s, '.')
 	if idx < 0 {
 		return fmt.Errorf("invalid object name: %q", s)
@@ -37,10 +37,7 @@ func (o *ObjectSet) Set(s string) error {
 		GoName:       s[idx+1:],
 	}
 
-	if o == nil {
-		*o = make(ObjectSet)
-	}
-	(*o)[ident] = true
+	o[ident] = true
 	return nil
 }