diff --git a/packages/builders/__tests__/messages/fileBody.test.ts b/packages/builders/__tests__/messages/fileBody.test.ts
index 2759ce610f8b..4af96a382e86 100644
--- a/packages/builders/__tests__/messages/fileBody.test.ts
+++ b/packages/builders/__tests__/messages/fileBody.test.ts
@@ -6,7 +6,7 @@ import { AttachmentBuilder, MessageBuilder } from '../../src/index.js';
 test('AttachmentBuilder stores and exposes file data', () => {
 	const data = Buffer.from('hello world');
 	const attachment = new AttachmentBuilder()
-		.setId('0')
+		.setId(1)
 		.setFilename('greeting.txt')
 		.setFileData(data)
 		.setFileContentType('text/plain');
@@ -14,7 +14,7 @@ test('AttachmentBuilder stores and exposes file data', () => {
 	expect(attachment.getRawFile()).toStrictEqual({
 		contentType: 'text/plain',
 		data,
-		key: 'files[0]',
+		key: 'files[1]',
 		name: 'greeting.txt',
 	});
 
@@ -27,7 +27,7 @@ test('AttachmentBuilder stores and exposes file data', () => {
 test('MessageBuilder.toFileBody returns JSON body and files', () => {
 	const msg = new MessageBuilder().setContent('here is a file').addAttachments(
 		new AttachmentBuilder()
-			.setId('0')
+			.setId(0)
 			.setFilename('file.bin')
 			.setFileData(Buffer.from([1, 2, 3]))
 			.setFileContentType('application/octet-stream'),
@@ -47,7 +47,9 @@ test('MessageBuilder.toFileBody returns JSON body and files', () => {
 });
 
 test('MessageBuilder.toFileBody returns empty files when attachments reference existing uploads', () => {
-	const msg = new MessageBuilder().addAttachments(new AttachmentBuilder().setId('123').setFilename('existing.png'));
+	const msg = new MessageBuilder().addAttachments(
+		new AttachmentBuilder().setId('1234567890123456789').setFilename('existing.png'),
+	);
 
 	const { body, files } = msg.toFileBody();
 	expect(body).toEqual(msg.toJSON());
diff --git a/packages/builders/__tests__/messages/message.test.ts b/packages/builders/__tests__/messages/message.test.ts
index 3e05eecd08ac..963475b8280f 100644
--- a/packages/builders/__tests__/messages/message.test.ts
+++ b/packages/builders/__tests__/messages/message.test.ts
@@ -64,7 +64,7 @@ describe('Message', () => {
 				row.addPrimaryButtonComponents((button) => button.setCustomId('abc').setLabel('def')),
 			)
 			.setStickerIds('123', '456')
-			.addAttachments((attachment) => attachment.setId('hi!').setFilename('abc'))
+			.addAttachments((attachment) => attachment.setId(0).setFilename('abc'))
 			.setFlags(MessageFlags.Ephemeral)
 			.setEnforceNonce(false)
 			.updatePoll((poll) => poll.addAnswers({ poll_media: { text: 'foo' } }).setQuestion({ text: 'foo' }));
@@ -83,7 +83,7 @@ describe('Message', () => {
 				},
 			],
 			sticker_ids: ['123', '456'],
-			attachments: [{ id: 'hi!', filename: 'abc' }],
+			attachments: [{ id: 0, filename: 'abc' }],
 			flags: 64,
 			enforce_nonce: false,
 			poll: {
diff --git a/packages/builders/src/Assertions.ts b/packages/builders/src/Assertions.ts
index c672c95c08dc..50761780c245 100644
--- a/packages/builders/src/Assertions.ts
+++ b/packages/builders/src/Assertions.ts
@@ -3,6 +3,7 @@ import { z } from 'zod';
 
 export const idPredicate = z.int().min(0).max(2_147_483_647).optional();
 export const customIdPredicate = z.string().min(1).max(100);
+export const snowflakePredicate = z.string().regex(/^[1-9]\d{16,18}$/);
 
 export const memberPermissionsPredicate = z.coerce.bigint();
 
diff --git a/packages/builders/src/components/Assertions.ts b/packages/builders/src/components/Assertions.ts
index 67b9b44fc0c4..864a27d567a0 100644
--- a/packages/builders/src/components/Assertions.ts
+++ b/packages/builders/src/components/Assertions.ts
@@ -1,12 +1,12 @@
 import { ButtonStyle, ChannelType, ComponentType, SelectMenuDefaultValueType } from 'discord-api-types/v10';
 import { z } from 'zod';
-import { idPredicate, customIdPredicate } from '../Assertions.js';
+import { idPredicate, customIdPredicate, snowflakePredicate } from '../Assertions.js';
 
 const labelPredicate = z.string().min(1).max(80);
 
 export const emojiPredicate = z
 	.strictObject({
-		id: z.string().optional(),
+		id: snowflakePredicate.optional(),
 		name: z.string().min(2).max(32).optional(),
 		animated: z.boolean().optional(),
 	})
@@ -39,7 +39,7 @@ const buttonLinkPredicate = buttonPredicateBase.extend({
 
 const buttonPremiumPredicate = buttonPredicateBase.extend({
 	style: z.literal(ButtonStyle.Premium),
-	sku_id: z.string(),
+	sku_id: snowflakePredicate,
 });
 
 export const buttonPredicate = z.discriminatedUnion('style', [
@@ -64,7 +64,7 @@ export const selectMenuChannelPredicate = selectMenuBasePredicate.extend({
 	type: z.literal(ComponentType.ChannelSelect),
 	channel_types: z.enum(ChannelType).array().optional(),
 	default_values: z
-		.object({ id: z.string(), type: z.literal(SelectMenuDefaultValueType.Channel) })
+		.object({ id: snowflakePredicate, type: z.literal(SelectMenuDefaultValueType.Channel) })
 		.array()
 		.max(25)
 		.optional(),
@@ -74,7 +74,7 @@ export const selectMenuMentionablePredicate = selectMenuBasePredicate.extend({
 	type: z.literal(ComponentType.MentionableSelect),
 	default_values: z
 		.object({
-			id: z.string(),
+			id: snowflakePredicate,
 			type: z.literal([SelectMenuDefaultValueType.Role, SelectMenuDefaultValueType.User]),
 		})
 		.array()
@@ -85,7 +85,7 @@ export const selectMenuMentionablePredicate = selectMenuBasePredicate.extend({
 export const selectMenuRolePredicate = selectMenuBasePredicate.extend({
 	type: z.literal(ComponentType.RoleSelect),
 	default_values: z
-		.object({ id: z.string(), type: z.literal(SelectMenuDefaultValueType.Role) })
+		.object({ id: snowflakePredicate, type: z.literal(SelectMenuDefaultValueType.Role) })
 		.array()
 		.max(25)
 		.optional(),
@@ -142,7 +142,7 @@ export const selectMenuStringPredicate = selectMenuBasePredicate
 export const selectMenuUserPredicate = selectMenuBasePredicate.extend({
 	type: z.literal(ComponentType.UserSelect),
 	default_values: z
-		.object({ id: z.string(), type: z.literal(SelectMenuDefaultValueType.User) })
+		.object({ id: snowflakePredicate, type: z.literal(SelectMenuDefaultValueType.User) })
 		.array()
 		.max(25)
 		.optional(),
diff --git a/packages/builders/src/messages/Assertions.ts b/packages/builders/src/messages/Assertions.ts
index 32f97512ef18..a913deac8d6b 100644
--- a/packages/builders/src/messages/Assertions.ts
+++ b/packages/builders/src/messages/Assertions.ts
@@ -1,6 +1,7 @@
 import { Buffer } from 'node:buffer';
 import { AllowedMentionsTypes, ComponentType, MessageFlags, MessageReferenceType } from 'discord-api-types/v10';
 import { z } from 'zod';
+import { snowflakePredicate } from '../Assertions.js';
 import { embedPredicate } from './embed/Assertions.js';
 import { pollPredicate } from './poll/Assertions.js';
 
@@ -15,7 +16,7 @@ export const rawFilePredicate = z.object({
 
 export const attachmentPredicate = z.object({
 	// As a string it only makes sense for edits when we do have an attachment snowflake
-	id: z.union([z.string(), z.number()]),
+	id: z.union([snowflakePredicate, z.number()]),
 	description: z.string().max(1_024).optional(),
 	duration_secs: z
 		.number()