diff --git a/package.json b/package.json
index 1a3c0fe0..7a606f34 100644
--- a/package.json
+++ b/package.json
@@ -27,6 +27,7 @@
 		"@testing-library/svelte": "3.2.1",
 		"@types/mermaid": "8.2.9",
 		"@types/pako": "1.0.3",
+		"@types/uuid": "^8.3.4",
 		"@typescript-eslint/eslint-plugin": "5.34.0",
 		"@typescript-eslint/parser": "5.34.0",
 		"@vitest/ui": "0.22.1",
@@ -75,7 +76,8 @@
 		"monaco-mermaid": "1.0.6",
 		"pako": "2.0.4",
 		"random-word-slugs": "0.1.6",
-		"svg-pan-zoom": "^3.6.1"
+		"svg-pan-zoom": "^3.6.1",
+		"uuid": "^8.3.2"
 	},
 	"lint-staged": {
 		"*.{ts,svelte,js,css,md,json}": [
diff --git a/src/lib/components/history/history.svelte b/src/lib/components/history/history.svelte
index 3e434fa9..525fa3e6 100644
--- a/src/lib/components/history/history.svelte
+++ b/src/lib/components/history/history.svelte
@@ -77,11 +77,11 @@
 		}
 	};
 
-	const clearHistory = (date?: number): void => {
-		if (!date && !prompt('Clear all saved items?')) {
+	const clearHistory = (id?: string): void => {
+		if (!id && !prompt('Clear all saved items?')) {
 			return;
 		}
-		clearHistoryData(date);
+		clearHistoryData(id);
 	};
 
 	const restoreHistoryItem = (state: State): void => {
@@ -147,7 +147,7 @@
 	</div>
 	<ul class="p-2 space-y-2 overflow-auto h-56" id="historyList">
 		{#if $historyStore.length > 0}
-			{#each $historyStore as { state, time, name, url, type }}
+			{#each $historyStore as { id, state, time, name, url, type }}
 				<li class="rounded p-2 shadow flex-col">
 					<div class="flex">
 						<div class="flex-1">
@@ -168,7 +168,7 @@
 							<button class="btn btn-success" on:click={() => restoreHistoryItem(state)}
 								><i class="fas fa-undo mr-1" />Restore</button>
 							{#if type !== 'loader'}
-								<button class="btn btn-error" on:click={() => clearHistory(time)}
+								<button class="btn btn-error" on:click={() => clearHistory(id)}
 									><i class="fas fa-trash-alt mr-1" />Delete</button>
 							{/if}
 						</div>
diff --git a/src/lib/components/history/history.ts b/src/lib/components/history/history.ts
index ffdd81fa..afcc8574 100644
--- a/src/lib/components/history/history.ts
+++ b/src/lib/components/history/history.ts
@@ -2,7 +2,8 @@ import { derived, writable, get } from 'svelte/store';
 import type { Readable, Writable } from 'svelte/store';
 import { persist, localStorage } from '@macfja/svelte-persistent-store';
 import { generateSlug } from 'random-word-slugs';
-import type { HistoryEntry, HistoryType } from '$lib/types';
+import type { HistoryEntry, HistoryType, Optional } from '$lib/types';
+import { v4 as uuidV4 } from 'uuid';
 
 const MAX_AUTO_HISTORY_LENGTH = 30;
 
@@ -41,28 +42,37 @@ export const historyStore: Readable<HistoryEntry[]> = derived(
 	}
 );
 
-export const addHistoryEntry = (entry: HistoryEntry): void => {
+export const addHistoryEntry = (entryToAdd: Optional<HistoryEntry, 'id'>): void => {
+	const entry: HistoryEntry = {
+		...entryToAdd,
+		id: uuidV4()
+	};
+
 	if (entry.type === 'loader') {
 		loaderHistoryStore.update((entries) => [entry, ...entries]);
 		return;
 	}
-	entry.name = generateSlug(2);
-	if (entry.type !== 'auto') {
+
+	if (!entry.name) {
+		entry.name = generateSlug(2);
+	}
+
+	if (entry.type === 'auto') {
+		autoHistoryStore.update((entries) => {
+			if (entries.length >= MAX_AUTO_HISTORY_LENGTH) {
+				entries = entries.slice(0, MAX_AUTO_HISTORY_LENGTH - 1);
+			}
+			return [entry, ...entries];
+		});
+	} else if (entry.type === 'manual') {
 		manualHistoryStore.update((entries) => [entry, ...entries]);
-		return;
 	}
-	autoHistoryStore.update((entries) => {
-		if (entries.length === MAX_AUTO_HISTORY_LENGTH) {
-			entries.pop();
-		}
-		return [entry, ...entries];
-	});
 };
 
-export const clearHistoryData = (time?: number): void => {
+export const clearHistoryData = (idToClear?: string): void => {
 	(get(historyModeStore) === 'auto' ? autoHistoryStore : manualHistoryStore).update((entries) => {
 		if (get(historyModeStore) !== 'loader') {
-			entries = entries.filter((entry) => time && entry.time != time);
+			entries = entries.filter(({ id }) => idToClear && id != idToClear);
 		}
 		return entries;
 	});
@@ -77,6 +87,46 @@ export const getPreviousState = (auto: boolean): string => {
 };
 
 export const restoreHistory = (data: HistoryEntry[]) => {
-	// Should this replace the current history or append to it?
-	manualHistoryStore.set(data);
+	const entries = data.filter(validateEntry);
+	const invalidEntryCount = data.length - entries.length;
+	if (invalidEntryCount > 0) {
+		console.error(`${invalidEntryCount} invalid history entries were removed.`);
+		console.error(data);
+	}
+	if (entries.length > 0) {
+		let entryCount = 0;
+		(entries[0].type === 'auto' ? autoHistoryStore : manualHistoryStore).update((existing) => {
+			const existingIDs = new Set(existing.map(({ id }) => id));
+			const newEntries = entries.filter(({ id }) => !existingIDs.has(id));
+			entryCount = newEntries.length;
+			const combined = [...existing, ...newEntries];
+			combined.sort((a, b) => b.time - a.time);
+			return combined;
+		});
+
+		alert(
+			`${entryCount} entries restored. ${invalidEntryCount} invalid, ${
+				entries.length - entryCount
+			} duplicates.`
+		);
+	} else {
+		alert('No valid entries found.');
+	}
+};
+
+export const injectHistoryIDs = (): void => {
+	const setIDs = (entries: HistoryEntry[]) => {
+		for (const entry of entries) {
+			if (!entry.id) {
+				entry.id = uuidV4();
+			}
+		}
+		return entries;
+	};
+	autoHistoryStore.update(setIDs);
+	manualHistoryStore.update(setIDs);
+};
+
+const validateEntry = (entry: HistoryEntry): boolean => {
+	return entry.type && entry.state && entry.time && true;
 };
diff --git a/src/lib/types.d.ts b/src/lib/types.d.ts
index 1aaf954a..806d1f20 100644
--- a/src/lib/types.d.ts
+++ b/src/lib/types.d.ts
@@ -68,13 +68,16 @@ export interface LoaderConfig {
 	config: GistLoaderConfig | FileLoaderConfig;
 }
 export type HistoryType = 'auto' | 'manual' | 'loader';
-export interface HistoryEntry {
-	state: State;
-	time: number;
-	name?: string;
-	type: HistoryType;
-	url?: string;
-}
+export type HistoryEntry = { id: string; state: State; time: number; url?: string } & (
+	| {
+			type: 'loader';
+			name: string;
+	  }
+	| {
+			type: HistoryType;
+			name?: string;
+	  }
+);
 
 export interface DocConfig {
 	[key: string]: {
@@ -84,3 +87,4 @@ export interface DocConfig {
 }
 
 export type Loader = (url: string) => Promise<State>;
+export type Optional<T, K extends keyof T> = Pick<Partial<T>, K> & Omit<T, K>;
diff --git a/src/lib/util/migrations.ts b/src/lib/util/migrations.ts
new file mode 100644
index 00000000..6b477746
--- /dev/null
+++ b/src/lib/util/migrations.ts
@@ -0,0 +1,32 @@
+import { writable, get, type Writable } from 'svelte/store';
+import { persist, localStorage } from '@macfja/svelte-persistent-store';
+import { injectHistoryIDs } from '$lib/components/history/history';
+
+interface MigrationState {
+	version: number;
+}
+
+const migrations: { [key: string]: () => void } = {
+	injectHistoryIDs
+};
+
+const migrationStore: Writable<MigrationState> = persist(
+	writable({ version: -1 }),
+	localStorage(),
+	'migrations'
+);
+
+export const applyMigrations = (): void => {
+	const { version }: MigrationState = get(migrationStore);
+	const allMigrations = Object.entries(migrations);
+	if (version === allMigrations.length - 1) {
+		return;
+	}
+	console.log(`Current migration version: v${version}. Migrating to v${allMigrations.length - 1}.`);
+	for (let i = version + 1; i < allMigrations.length; i++) {
+		const [key, fn] = allMigrations[i];
+		console.log(`Applying migration ${i}: ${key}.`);
+		fn();
+		migrationStore.set({ version: i });
+	}
+};
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 26aa808c..097ea9fb 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -6,10 +6,12 @@
 	import { setTheme, themeStore } from '$lib/util/theme';
 	import { toggleDarkTheme } from '$lib/util/state';
 	import { initHandler } from '$lib/util/util';
+	import { applyMigrations } from '$lib/util/migrations';
 
 	// This can be removed once https://github.com/sveltejs/kit/issues/1612 is fixed.
 	// Then move it into src and vite will bundle it automatically.
 	onMount(() => {
+		applyMigrations();
 		window.addEventListener('hashchange', async (ev) => {
 			await initHandler();
 		});
diff --git a/yarn.lock b/yarn.lock
index d0eaf998..7bd143d0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -458,6 +458,11 @@
   dependencies:
     "@types/jest" "*"
 
+"@types/uuid@^8.3.4":
+  version "8.3.4"
+  resolved "https://registry.yarnpkg.com/@types/uuid/-/uuid-8.3.4.tgz#bd86a43617df0594787d38b735f55c805becf1bc"
+  integrity sha512-c/I8ZRb51j+pYGAu5CrFMRxqZ2ke4y2grEBO5AUjgSkSk+qT2Ea+OdWElz/OiMf5MNpn2b17kuVBwZLQJXzihw==
+
 "@types/yauzl@^2.9.1":
   version "2.9.1"
   resolved "https://registry.npmjs.org/@types/yauzl/-/yauzl-2.9.1.tgz"