diff --git a/packages/common/types.ts b/packages/common/types.ts
index 1a52037..551a584 100644
--- a/packages/common/types.ts
+++ b/packages/common/types.ts
@@ -217,6 +217,9 @@ export class RequestBuilder {
       authRequest.isAnon = false;
       authRequest.isOptional = authRequest.isOptional ?? false;
       authRequest.userId = authRequest.userId ?? "0";
+      if (authRequest.authType === AuthType.EVM_ACCOUNT) {
+        authRequest.userId = authRequest.userId.toLowerCase();
+      }
       authRequest.extraData = authRequest.extraData ?? "";
 
       if (authRequest.userId === "0") {
diff --git a/packages/sismo-connect-client/src/common-types.ts b/packages/sismo-connect-client/src/common-types.ts
index 1a52037..551a584 100644
--- a/packages/sismo-connect-client/src/common-types.ts
+++ b/packages/sismo-connect-client/src/common-types.ts
@@ -217,6 +217,9 @@ export class RequestBuilder {
       authRequest.isAnon = false;
       authRequest.isOptional = authRequest.isOptional ?? false;
       authRequest.userId = authRequest.userId ?? "0";
+      if (authRequest.authType === AuthType.EVM_ACCOUNT) {
+        authRequest.userId = authRequest.userId.toLowerCase();
+      }
       authRequest.extraData = authRequest.extraData ?? "";
 
       if (authRequest.userId === "0") {
diff --git a/packages/sismo-connect-client/tests/sismo-connect.test.ts b/packages/sismo-connect-client/tests/sismo-connect.test.ts
index 59bf035..cf1f3d8 100644
--- a/packages/sismo-connect-client/tests/sismo-connect.test.ts
+++ b/packages/sismo-connect-client/tests/sismo-connect.test.ts
@@ -1,4 +1,11 @@
-import { ClaimRequest, SismoConnect, SismoConnectClient, SismoConnectConfig } from "../src";
+import {
+  Auth,
+  AuthType,
+  ClaimRequest,
+  SismoConnect,
+  SismoConnectClient,
+  SismoConnectConfig,
+} from "../src";
 
 describe("Sismo Connect Client", () => {
   let appId: string;
@@ -71,4 +78,24 @@ describe("Sismo Connect Client", () => {
       `https://vault-beta.sismo.io/connect?version=sismo-connect-v1.1&appId=0xf68985adfc209fafebfb1a956913e7fa&claims=[{\"groupId\":\"0x1\",\"claimType\":0,\"extraData\":\"\",\"groupTimestamp\":\"latest\",\"value\":1}]&vault={\"impersonate\":[\"0x123\",\"0x345\"]}&compressed=true`
     );
   });
+
+  it("should put EVM account userIds in lower case", async () => {
+    const requestLink = sismoConnect.getRequestLink({
+      auths: [
+        {
+          authType: AuthType.EVM_ACCOUNT,
+          userId: "0xAa1BcC",
+        },
+        {
+          authType: AuthType.EVM_ACCOUNT,
+          userId: "0xDaDBcD",
+        },
+      ],
+    });
+    const url = new URL(requestLink);
+    let params = new URLSearchParams(url.search);
+    let auths = JSON.parse(params.get("auths") as string) as Auth[];
+    expect(auths[0].userId).toEqual("0xaa1bcc");
+    expect(auths[1].userId).toEqual("0xdadbcd");
+  });
 });
diff --git a/packages/sismo-connect-server/src/common-types.ts b/packages/sismo-connect-server/src/common-types.ts
index 1a52037..551a584 100644
--- a/packages/sismo-connect-server/src/common-types.ts
+++ b/packages/sismo-connect-server/src/common-types.ts
@@ -217,6 +217,9 @@ export class RequestBuilder {
       authRequest.isAnon = false;
       authRequest.isOptional = authRequest.isOptional ?? false;
       authRequest.userId = authRequest.userId ?? "0";
+      if (authRequest.authType === AuthType.EVM_ACCOUNT) {
+        authRequest.userId = authRequest.userId.toLowerCase();
+      }
       authRequest.extraData = authRequest.extraData ?? "";
 
       if (authRequest.userId === "0") {