diff --git a/lib/actions/registration.js b/lib/actions/registration.js
index 93c612fc2..fff0b895f 100644
--- a/lib/actions/registration.js
+++ b/lib/actions/registration.js
@@ -39,7 +39,7 @@ const validateRegistrationAccessToken = [
     );
     ctx.assert(regAccessToken, new InvalidToken('token not found'));
 
-    const client = await ctx.oidc.provider.Client.find(ctx.params.clientId);
+    const client = await ctx.oidc.provider.Client.find(decodeURIComponent(ctx.params.clientId));
 
     if (!client || client.clientId !== regAccessToken.clientId) {
       await regAccessToken.destroy();
@@ -139,7 +139,7 @@ module.exports = {
       if (rat) {
         Object.assign(ctx.body, {
           registration_client_uri: ctx.oidc.urlFor('client', {
-            clientId: properties.client_id,
+            clientId: encodeURIComponent(properties.client_id),
           }),
           registration_access_token: await rat.save(),
         });
diff --git a/test/client_id_uri/client_id_uri.config.js b/test/client_id_uri/client_id_uri.config.js
new file mode 100644
index 000000000..037aa9aa2
--- /dev/null
+++ b/test/client_id_uri/client_id_uri.config.js
@@ -0,0 +1,22 @@
+const cloneDeep = require('lodash/cloneDeep');
+const merge = require('lodash/merge');
+
+const nanoid = require('../../lib/helpers/nanoid');
+const config = cloneDeep(require('../default.config'));
+
+merge(config.features, {
+  registration: {
+    enabled: true,
+    rotateRegistrationAccessToken: false,
+    idFactory() {
+      return new URL(`https://repo.clients.com/path?id=${nanoid()}`).href;
+    },
+  },
+  registrationManagement: {
+    enabled: true,
+  },
+});
+
+module.exports = {
+  config,
+};
diff --git a/test/client_id_uri/client_id_uri.test.js b/test/client_id_uri/client_id_uri.test.js
new file mode 100644
index 000000000..4c12fc724
--- /dev/null
+++ b/test/client_id_uri/client_id_uri.test.js
@@ -0,0 +1,59 @@
+const { expect } = require('chai');
+
+const bootstrap = require('../test_helper');
+
+describe('registration management with client_id as URI', () => {
+  before(bootstrap(__dirname));
+
+  it('returns client_id as a URI string', async function () {
+    let client_id;
+    let registration_client_uri;
+    let registration_access_token;
+
+    await this.agent.post('/reg')
+      .send({
+        redirect_uris: ['https://client.example.com/cb'],
+      })
+      .expect(201)
+      .expect((response) => {
+        ({ client_id, registration_access_token, registration_client_uri } = response.body);
+
+        const parsed = new URL(registration_client_uri);
+        expect(parsed.search).to.be.empty;
+        const i = parsed.pathname.indexOf('/reg/');
+        expect(parsed.pathname.slice(i + 5)).to.equal(encodeURIComponent(client_id));
+      });
+
+    await this.agent.get(new URL(registration_client_uri).pathname)
+      .auth(registration_access_token, { type: 'bearer' })
+      .expect(200)
+      .expect((response) => {
+        ({ registration_client_uri } = response.body);
+
+        const parsed = new URL(registration_client_uri);
+        expect(parsed.search).to.be.empty;
+        const i = parsed.pathname.indexOf('/reg/');
+        expect(parsed.pathname.slice(i + 5)).to.equal(encodeURIComponent(client_id));
+      });
+
+    await this.agent.put(new URL(registration_client_uri).pathname)
+      .auth(registration_access_token, { type: 'bearer' })
+      .send({
+        client_id,
+        redirect_uris: ['https://client.example.com/cb2'],
+      })
+      .expect(200)
+      .expect((response) => {
+        ({ registration_client_uri } = response.body);
+
+        const parsed = new URL(registration_client_uri);
+        expect(parsed.search).to.be.empty;
+        const i = parsed.pathname.indexOf('/reg/');
+        expect(parsed.pathname.slice(i + 5)).to.equal(encodeURIComponent(client_id));
+      });
+
+    await this.agent.delete(new URL(registration_client_uri).pathname)
+      .auth(registration_access_token, { type: 'bearer' })
+      .expect(204);
+  });
+});