diff --git a/src/types/files/fileChecksums.ts b/src/types/files/fileChecksums.ts
index 87db86e9e..01739e373 100644
--- a/src/types/files/fileChecksums.ts
+++ b/src/types/files/fileChecksums.ts
@@ -1,5 +1,5 @@
 import crypto from 'node:crypto';
-import { Stream } from 'node:stream';
+import { Readable, Stream } from 'node:stream';
 
 import { crc32 } from '@node-rs/crc32';
 
@@ -17,6 +17,17 @@ export interface ChecksumProps {
 }
 
 export default class FileChecksums {
+  public static async hashData(
+    data: Buffer | string,
+    checksumBitmask: number,
+  ): Promise<ChecksumProps> {
+    const readable = new Readable();
+    readable.push(data);
+    // eslint-disable-next-line unicorn/no-null
+    readable.push(null);
+    return this.hashStream(readable, checksumBitmask);
+  }
+
   public static async hashStream(
     stream: Stream,
     checksumBitmask: number,
diff --git a/src/types/patches/bpsPatch.ts b/src/types/patches/bpsPatch.ts
index bde039f89..ca19ba512 100644
--- a/src/types/patches/bpsPatch.ts
+++ b/src/types/patches/bpsPatch.ts
@@ -1,6 +1,7 @@
 import FilePoly from '../../polyfill/filePoly.js';
 import fsPoly from '../../polyfill/fsPoly.js';
 import File from '../files/file.js';
+import FileChecksums, { ChecksumBitmask } from '../files/fileChecksums.js';
 import Patch from './patch.js';
 
 enum BPSAction {
@@ -27,15 +28,24 @@ export default class BPSPatch extends Patch {
     await file.extractToTempFilePoly('r', async (patchFile) => {
       patchFile.seek(BPSPatch.FILE_SIGNATURE.length);
       await Patch.readUpsUint(patchFile); // source size
-      targetSize = await Patch.readUpsUint(patchFile); // target size
+      targetSize = await Patch.readUpsUint(patchFile);
 
       patchFile.seek(patchFile.getSize() - 12);
       crcBefore = (await patchFile.readNext(4)).reverse().toString('hex');
       crcAfter = (await patchFile.readNext(4)).reverse().toString('hex');
+
+      // Validate the patch contents
+      const patchChecksumExpected = (await patchFile.readNext(4)).reverse().toString('hex');
+      patchFile.seek(0);
+      const patchData = await patchFile.readNext(patchFile.getSize() - 4);
+      const patchChecksumsActual = await FileChecksums.hashData(patchData, ChecksumBitmask.CRC32);
+      if (patchChecksumsActual.crc32 !== patchChecksumExpected) {
+        throw new Error(`BPS patch is invalid, CRC of contents (${patchChecksumsActual.crc32}) doesn't match expected (${patchChecksumExpected}): ${file.toString()}`);
+      }
     });
 
     if (crcBefore.length !== 8 || crcAfter.length !== 8) {
-      throw new Error(`Couldn't parse base file CRC for patch: ${file.toString()}`);
+      throw new Error(`couldn't parse base file CRC for patch: ${file.toString()}`);
     }
 
     return new BPSPatch(file, crcBefore, crcAfter, targetSize);
diff --git a/src/types/patches/upsPatch.ts b/src/types/patches/upsPatch.ts
index debe5aa16..b2c28b4d3 100644
--- a/src/types/patches/upsPatch.ts
+++ b/src/types/patches/upsPatch.ts
@@ -1,6 +1,7 @@
 import FilePoly from '../../polyfill/filePoly.js';
 import fsPoly from '../../polyfill/fsPoly.js';
 import File from '../files/file.js';
+import FileChecksums, { ChecksumBitmask } from '../files/fileChecksums.js';
 import Patch from './patch.js';
 
 /**
@@ -24,11 +25,20 @@ export default class UPSPatch extends Patch {
     await file.extractToTempFilePoly('r', async (patchFile) => {
       patchFile.seek(UPSPatch.FILE_SIGNATURE.length);
       await Patch.readUpsUint(patchFile); // source size
-      targetSize = await Patch.readUpsUint(patchFile); // target size
+      targetSize = await Patch.readUpsUint(patchFile);
 
       patchFile.seek(patchFile.getSize() - 12);
       crcBefore = (await patchFile.readNext(4)).reverse().toString('hex');
       crcAfter = (await patchFile.readNext(4)).reverse().toString('hex');
+
+      // Validate the patch contents
+      const patchChecksumExpected = (await patchFile.readNext(4)).reverse().toString('hex');
+      patchFile.seek(0);
+      const patchData = await patchFile.readNext(patchFile.getSize() - 4);
+      const patchChecksumsActual = await FileChecksums.hashData(patchData, ChecksumBitmask.CRC32);
+      if (patchChecksumsActual.crc32 !== patchChecksumExpected) {
+        throw new Error(`UPS patch is invalid, CRC of contents (${patchChecksumsActual.crc32}) doesn't match expected (${patchChecksumExpected}): ${file.toString()}`);
+      }
     });
 
     if (crcBefore.length !== 8 || crcAfter.length !== 8) {
diff --git a/test/types/patches/bpsPatch.test.ts b/test/types/patches/bpsPatch.test.ts
index 16073913b..f99cd01a7 100644
--- a/test/types/patches/bpsPatch.test.ts
+++ b/test/types/patches/bpsPatch.test.ts
@@ -21,7 +21,7 @@ describe('constructor', () => {
     Buffer.from('foobar'),
   ])('should throw on bad patch: %s', async (patchContents) => {
     const patchFile = await writeTemp('patch.bps', patchContents);
-    await expect(BPSPatch.patchFrom(patchFile)).rejects.toThrow(/couldn't parse/i);
+    await expect(BPSPatch.patchFrom(patchFile)).rejects.toThrow();
   });
 
   test.each([
diff --git a/test/types/patches/upsPatch.test.ts b/test/types/patches/upsPatch.test.ts
index 3e1f47287..af06f6685 100644
--- a/test/types/patches/upsPatch.test.ts
+++ b/test/types/patches/upsPatch.test.ts
@@ -21,7 +21,7 @@ describe('constructor', () => {
     Buffer.from('foobar'),
   ])('should throw on bad patch: %s', async (patchContents) => {
     const patchFile = await writeTemp('patch.bps', patchContents);
-    await expect(UPSPatch.patchFrom(patchFile)).rejects.toThrow(/couldn't parse/i);
+    await expect(UPSPatch.patchFrom(patchFile)).rejects.toThrow();
   });
 
   test.each([