diff --git a/src/Frigid.ts b/src/Frigid.ts
index 2bb9a8c..b849a9d 100644
--- a/src/Frigid.ts
+++ b/src/Frigid.ts
@@ -1,6 +1,6 @@
 import { existsSync, readFileSync, writeFileSync } from "fs";
 import { reverseLookup } from "./reverseLookup.js";
-import Serializable from "./Serializable.js";
+import Serializable, { INVOKE_CTOR } from "./Serializable.js";
 
 const PERSIST_LOCATION = Symbol('PERSIST_LOCATION');
 
@@ -36,6 +36,7 @@ export default class Frigid extends Serializable {
 }
 
 function walk(obj, transform, done = new Map()) {
+	if(obj === null || obj === undefined) return;
 	if(obj instanceof Serializable) {
 		transform(obj);
 	}
@@ -57,7 +58,7 @@ function finalze(instance, filename) {
 
 	walk(instance, (obj) => {
 		// console.log(obj instanceof Serializable)
-		(obj as any).ctor?.();
+		obj[INVOKE_CTOR]();
 	});
 
 	instance.sync();
diff --git a/src/Serializable.ts b/src/Serializable.ts
index 00eb094..79bf4bf 100644
--- a/src/Serializable.ts
+++ b/src/Serializable.ts
@@ -2,11 +2,26 @@
 import { existsSync, readFileSync, writeFileSync } from 'fs';
 import { reverseLookup } from './reverseLookup.js';
 
+export const CTOR_CALLED = Symbol('CTOR_CALLED');
+export const INVOKE_CTOR = Symbol('INVOKE_CTOR');
+
 export default class Serializable {
 
+	[CTOR_CALLED] = false;
+
 	// takes as many args as it needs to (so subclasses can
 	// define their own constructor, with any number of args)
-	constructor(...args) {}
+	constructor(...args) {
+		this[INVOKE_CTOR]();
+	}
+
+	[INVOKE_CTOR] () {
+		const call = !this[CTOR_CALLED];
+		this[CTOR_CALLED] = true;
+		if(call) {
+			(this as any).ctor?.();
+		}
+	}
 
 	// things that need to be stored only in cold
 	// storage are keyed with a special prefix
@@ -148,6 +163,7 @@ export default class Serializable {
 				if(key === Serializable.CLASS_REFERENCE) delete obj[key];
 				const val = obj[key];
 				if(typeof val === 'object') {
+					if(val === null || val === undefined) return obj;
 					if(Serializable.INSTANCE_REFERENCE in val) {
 						const refId = val[Serializable.INSTANCE_REFERENCE];
 						if(instances.has(refId)) {
diff --git a/test/Frigid.js b/test/Frigid.js
index 200d7df..fbbcc27 100644
--- a/test/Frigid.js
+++ b/test/Frigid.js
@@ -16,8 +16,7 @@ class Sub extends Serializable {
 
 class Test extends Frigid {
 	foo = 'bar';
-
-	test = new Sub();
+	test = null;
 
 	static serializationDependencies() {
 		return [ Sub ];
@@ -30,6 +29,7 @@ class Test extends Frigid {
 
 	ctor() {
 		trackingData.ctor ++;
+		this.test ??= new Sub();
 	}
 }
 
@@ -46,9 +46,9 @@ expect(test.sync.bind(test)).to.not.throw();
 expect(existsSync(filepath)).to.be.true;
 expect(readFileSync(filepath).toString()).to.not.be.empty;
 
+expect(trackingData.ctor).to.equal(1);
 expect(trackingData.constructorCalls).to.equal(1);
 expect(trackingData.subCtor).to.equal(1);
-expect(trackingData.ctor).to.equal(1);
 
 const retest = Test.create(filepath);