diff --git a/src/commands/init.ts b/src/commands/init.ts
index 9c5fc46..efbec11 100644
--- a/src/commands/init.ts
+++ b/src/commands/init.ts
@@ -8,6 +8,10 @@ import { installPrepareCommitMsgHook } from '../git/hook.js';
 
 const CUSTOM_KEY = '__custom__';
 
+export function normalizeBaseUrl(value: string): string {
+  return value.replace(/\/+$/, '');
+}
+
 export function buildApiKeyPrompt(existingKey: string, apiKeyEnv: string) {
   return {
     message: `Enter your API key (will be stored in config), or leave blank to use ${pc.cyan(`$${apiKeyEnv}`)} env var:`,
@@ -78,7 +82,7 @@ export async function initCommand(options: { installHook?: boolean } = {}): Prom
       outro('Setup cancelled.');
       return;
     }
-    baseUrl = urlResult;
+    baseUrl = normalizeBaseUrl(urlResult);
     apiKeyEnv = 'CUSTOM_API_KEY';
     needsApiKey = true;
   } else {
diff --git a/tests/init-base-url.test.mjs b/tests/init-base-url.test.mjs
new file mode 100644
index 0000000..1c2f4f2
--- /dev/null
+++ b/tests/init-base-url.test.mjs
@@ -0,0 +1,56 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { initCommand, normalizeBaseUrl } from '../dist/commands/init.js';
+
+test('handles single trailing slash', () => {
+  assert.equal(normalizeBaseUrl('https://api.example.com/v1/'), 'https://api.example.com/v1');
+});
+
+test('trims multiple trailing slashes from custom base URLs', () => {
+  assert.equal(normalizeBaseUrl('https://api.example.com/v1///'), 'https://api.example.com/v1');
+});
+
+test('preserves custom base URLs without trailing slashes', () => {
+  assert.equal(normalizeBaseUrl('https://api.example.com/v1'), 'https://api.example.com/v1');
+});
+
+test('initCommand saves normalized custom provider base URL', async () => {
+  const savedConfigs = [];
+  const selectedValues = ['__custom__', 'custom-model'];
+  const textValues = ['https://api.example.com/v1/', 'test-api-key', '50'];
+  const spinnerStub = {
+    start() {},
+    stop() {},
+  };
+
+  await initCommand(
+    {},
+    {
+      intro() {},
+      outro() {},
+      select: async () => selectedValues.shift(),
+      text: async () => textValues.shift(),
+      confirm: async () => false,
+      spinner: () => spinnerStub,
+      isCancel: () => false,
+      configExists: () => false,
+      fetchModels: async (provider, baseUrl) => {
+        assert.equal(provider, '__custom__');
+        assert.equal(baseUrl, 'https://api.example.com/v1');
+        return ['custom-model'];
+      },
+      saveConfig: async (config) => {
+        savedConfigs.push(config);
+      },
+      testConnection: async (config) => {
+        assert.equal(config.baseUrl, 'https://api.example.com/v1');
+        return config.model;
+      },
+    },
+  );
+
+  assert.equal(savedConfigs.length, 1);
+  assert.equal(savedConfigs[0].provider, '__custom__');
+  assert.equal(savedConfigs[0].baseUrl, 'https://api.example.com/v1');
+});