diff --git a/src/tracer/Tracer.ts b/src/tracer/Tracer.ts
index 71d81d0..a82233b 100644
--- a/src/tracer/Tracer.ts
+++ b/src/tracer/Tracer.ts
@@ -1,54 +1,54 @@
-import type { SpanEvent } from './types.js';
-import { IdSortable, utils as idUtils } from '@matrixai/id';
+import type { SpanEvent, SpanId } from './types.js';
+import { IdSortable } from '@matrixai/id';
 
 class Tracer {
-  protected activeSpans: Map<string, string> = new Map();
+  protected activeSpans: Map<SpanId, string> = new Map();
   protected queue: Array<SpanEvent> = [];
   protected resolveWaitChunksP: (() => void) | undefined;
   protected ended: boolean = false;
   protected idGen = new IdSortable();
+  protected shouldTrace = false;
 
-  protected nextId(): string {
+  protected nextId(): SpanId {
     const result = this.idGen.next();
     if (result.done || result.value == null) {
       throw new Error('Unexpected end of id generator');
     }
-    return idUtils.toMultibase(result.value, 'base64');
+    return result.value.toMultibase('base32hex') as SpanId;
   }
 
-  protected queueSpanEvent(evt: SpanEvent) {
+  protected queueSpanEvent(evt: SpanEvent): void {
+    if (!this.shouldTrace) return;
     this.queue.push(evt);
     if (this.resolveWaitChunksP != null) this.resolveWaitChunksP();
   }
 
-  public startSpan(name: string, parentSpanId?: string): string {
+  public startSpan(name: string, parentSpanId?: SpanId): SpanId {
     const spanId = this.nextId();
     this.activeSpans.set(spanId, name);
     this.queueSpanEvent({
       type: 'start',
-      id: this.nextId(),
-      spanId: spanId,
-      parentSpanId: parentSpanId,
+      id: spanId,
+      parentId: parentSpanId,
       name: name,
     });
     return spanId;
   }
 
-  public endSpan(spanId: string): void {
+  public endSpan(spanId: SpanId): void {
     const name = this.activeSpans.get(spanId);
     if (!name) return;
     this.activeSpans.delete(spanId);
     this.queueSpanEvent({
-      type: 'end',
+      type: 'stop',
       id: this.nextId(),
-      spanId: spanId,
-      name: name,
+      startId: spanId,
     });
   }
 
   public async traced<T>(
     name: string,
-    parentSpanId: string | undefined,
+    parentSpanId: SpanId | undefined,
     fn: () => T | Promise<T>,
   ): Promise<T> {
     const fnProm = async () => {
@@ -77,6 +77,13 @@ class Tracer {
       yield value;
     }
   }
+
+  public disableTracing(): void {
+    this.shouldTrace = false;
+    this.ended = true;
+    this.resolveWaitChunksP?.();
+    this.queue = [];
+  }
 }
 
 export default Tracer;
diff --git a/src/tracer/types.ts b/src/tracer/types.ts
index 74b75d4..ab8550f 100644
--- a/src/tracer/types.ts
+++ b/src/tracer/types.ts
@@ -1,12 +1,26 @@
-type Span = {
-  spanId: string;
-  name: string;
-  parentSpanId?: string;
+type SpanId = string & { readonly brand: unique symbol };
+
+/**
+ * A span is a virtual concept, not an actual object. A span is made up of
+ * multiple events. Each event gets its own ID. Each start event must be
+ * associated with a stop event, otherwise the span is considered to be
+ * ongoing.
+ */
+
+type SpanStart = {
+  type: 'start';
+  id: SpanId;
+  parentId?: SpanId;
+  name?: string;
 };
 
-type SpanEvent = Span & {
-  type: 'start' | 'end';
-  id: string;
+type SpanStop = {
+  type: 'stop';
+  id: SpanId;
+  startId: SpanId;
+  parentId?: SpanId;
 };
 
-export type { Span, SpanEvent };
+type SpanEvent = SpanStart | SpanStop;
+
+export type { SpanId, SpanEvent };
diff --git a/tests/asciinemaTest.ts b/tests/asciinemaTest.ts
index 88b6e2c..2b268ca 100644
--- a/tests/asciinemaTest.ts
+++ b/tests/asciinemaTest.ts
@@ -1,10 +1,11 @@
+import type { SpanId } from '#tracer/index.js';
 import fs from 'fs';
 import * as fc from 'fast-check';
 import tracer from '#tracer/index.js';
 
 let parentIndex = 0;
 let step = 0;
-let nestedIds: Array<string> = [];
+let nestedIds: Array<SpanId> = [];
 
 type Flags = {
   hasForkA: boolean;
@@ -18,9 +19,9 @@ type Flags = {
 };
 
 const current: {
-  parentId?: string;
-  forkAId?: string;
-  forkBId?: string;
+  parentId?: SpanId;
+  forkAId?: SpanId;
+  forkBId?: SpanId;
   flags: Flags;
 } = {
   flags: {