diff --git a/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java b/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
index 51f987e1fb..108cd7db02 100644
--- a/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
+++ b/runelite-client/src/main/java/net/runelite/client/rs/ClientLoader.java
@@ -259,7 +259,10 @@ public class ClientLoader implements Supplier<Applet>
 
 	private void updateVanilla(RSConfig config) throws IOException, VerificationException
 	{
-		Certificate[] jagexCertificateChain = getJagexCertificateChain();
+		Certificate[][] jagexCertificateChains = {
+			loadCertificateChain("jagex.crt"),
+			loadCertificateChain("jagex2021.crt")
+		};
 
 		// Get the mtime of the first thing in the vanilla cache
 		// we check this against what the server gives us to let us skip downloading and patching the whole thing
@@ -276,7 +279,7 @@ public class ClientLoader implements Supplier<Applet>
 				JarEntry je = vanillaCacheTest.getNextJarEntry();
 				if (je != null)
 				{
-					verifyJarEntry(je, jagexCertificateChain);
+					verifyJarEntry(je, jagexCertificateChains);
 					vanillaCacheMTime = je.getLastModifiedTime().toMillis();
 				}
 				else
@@ -355,7 +358,7 @@ public class ClientLoader implements Supplier<Applet>
 						}
 
 						networkJIS.skip(Long.MAX_VALUE);
-						verifyJarEntry(je, jagexCertificateChain);
+						verifyJarEntry(je, jagexCertificateChains);
 						long vanillaClientMTime = je.getLastModifiedTime().toMillis();
 						if (!vanillaCacheIsInvalid && vanillaClientMTime != vanillaCacheMTime)
 						{
@@ -372,7 +375,7 @@ public class ClientLoader implements Supplier<Applet>
 						{
 							// as with the request stream, its important to not early close vanilla too
 							JarInputStream vanillaCacheTest = new JarInputStream(Channels.newInputStream(vanilla));
-							verifyWholeJar(vanillaCacheTest, jagexCertificateChain);
+							verifyWholeJar(vanillaCacheTest, jagexCertificateChains);
 						}
 						catch (Exception e)
 						{
@@ -388,7 +391,7 @@ public class ClientLoader implements Supplier<Applet>
 						OutputStream out = Channels.newOutputStream(vanilla);
 						out.write(preRead.toByteArray());
 						copyStream.setOut(out);
-						verifyWholeJar(networkJIS, jagexCertificateChain);
+						verifyWholeJar(networkJIS, jagexCertificateChains);
 						copyStream.skip(Long.MAX_VALUE); // write the trailer to the file too
 						out.flush();
 						vanilla.truncate(vanilla.position());
@@ -557,9 +560,9 @@ public class ClientLoader implements Supplier<Applet>
 		return rs;
 	}
 
-	private static Certificate[] getJagexCertificateChain()
+	private static Certificate[] loadCertificateChain(String name)
 	{
-		try (InputStream in = ClientLoader.class.getResourceAsStream("jagex.crt"))
+		try (InputStream in = ClientLoader.class.getResourceAsStream(name))
 		{
 			CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
 			Collection<? extends Certificate> certificates = certificateFactory.generateCertificates(in);
@@ -571,28 +574,33 @@ public class ClientLoader implements Supplier<Applet>
 		}
 	}
 
-	private void verifyJarEntry(JarEntry je, Certificate[] certs) throws VerificationException
+	private void verifyJarEntry(JarEntry je, Certificate[][] chains) throws VerificationException
 	{
-		switch (je.getName())
+		if (je.getName().equals("META-INF/JAGEXLTD.SF") || je.getName().equals("META-INF/JAGEXLTD.RSA"))
 		{
-			case "META-INF/JAGEXLTD.SF":
-			case "META-INF/JAGEXLTD.RSA":
-				// You can't sign the signing files
-				return;
-			default:
-				if (!Arrays.equals(je.getCertificates(), certs))
-				{
-					throw new VerificationException("Unable to verify jar entry: " + je.getName());
-				}
+			// You can't sign the signing files
+			return;
 		}
+
+		// Jar entry must match one of the trusted certificate chains
+		Certificate[] entryCertificates = je.getCertificates();
+		for (Certificate[] chain : chains)
+		{
+			if (Arrays.equals(entryCertificates, chain))
+			{
+				return;
+			}
+		}
+
+		throw new VerificationException("Unable to verify jar entry: " + je.getName());
 	}
 
-	private void verifyWholeJar(JarInputStream jis, Certificate[] certs) throws IOException, VerificationException
+	private void verifyWholeJar(JarInputStream jis, Certificate[][] chains) throws IOException, VerificationException
 	{
 		for (JarEntry je; (je = jis.getNextJarEntry()) != null; )
 		{
 			jis.skip(Long.MAX_VALUE);
-			verifyJarEntry(je, certs);
+			verifyJarEntry(je, chains);
 		}
 	}
 }
diff --git a/runelite-client/src/main/resources/net/runelite/client/rs/jagex2021.crt b/runelite-client/src/main/resources/net/runelite/client/rs/jagex2021.crt
new file mode 100644
index 0000000000..39a381c29e
--- /dev/null
+++ b/runelite-client/src/main/resources/net/runelite/client/rs/jagex2021.crt
@@ -0,0 +1,83 @@
+-----BEGIN CERTIFICATE-----
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\ No newline at end of file