diff --git a/src/objects/BaseObject.ts b/src/objects/BaseObject.ts
index 6da279a..4877d97 100644
--- a/src/objects/BaseObject.ts
+++ b/src/objects/BaseObject.ts
@@ -25,7 +25,7 @@ import { BaseObjectParams } from '../interfaces/BaseObjectParams';
 import { EciVec3, Kilometers, SpaceObjectType } from '../types/types';
 
 export class BaseObject {
-  id?: number; // Unique ID
+  id: number;
   name: string;
   type: SpaceObjectType;
   position: EciVec3; // Where is the object
@@ -36,7 +36,7 @@ export class BaseObject {
   constructor(info: BaseObjectParams) {
     this.type = info.type ?? SpaceObjectType.UNKNOWN;
     this.name = info.name ?? 'Unknown';
-    this.id = info.id;
+    this.id = info.id ?? -1; // Default to -1 if no id is provided
     this.active = info.active ?? true;
 
     // Default to the center of the earth until position is calculated
diff --git a/test/objects/__snapshots__/GroundObject.test.ts.snap b/test/objects/__snapshots__/GroundObject.test.ts.snap
index 91b808f..ea02b85 100644
--- a/test/objects/__snapshots__/GroundObject.test.ts.snap
+++ b/test/objects/__snapshots__/GroundObject.test.ts.snap
@@ -36,7 +36,7 @@ exports[`GroundObject should create from geodetic 1`] = `
 GroundObject {
   "active": true,
   "alt": 0,
-  "id": undefined,
+  "id": -1,
   "lat": 0,
   "lon": 0,
   "name": "Unknown Ground Object",
diff --git a/test/objects/__snapshots__/Satellite.test.ts.snap b/test/objects/__snapshots__/Satellite.test.ts.snap
index 5e2e7bf..9924072 100644
--- a/test/objects/__snapshots__/Satellite.test.ts.snap
+++ b/test/objects/__snapshots__/Satellite.test.ts.snap
@@ -101,7 +101,7 @@ Satellite {
   "eccentricity": 0.0005168,
   "epochDay": 203.46960946,
   "epochYear": 22,
-  "id": undefined,
+  "id": -1,
   "inclination": 51.6415,
   "intlDes": "98067A",
   "meanAnomaly": 54.7009,