diff --git a/README.md b/README.md
index 28ea3a3d13..be9f5202cf 100644
--- a/README.md
+++ b/README.md
@@ -224,7 +224,6 @@ webExt.cmd.sign({
   userAgentString: 'YOUR-CUSTOM-USERAGENT',
   apiKey,
   apiSecret,
-  amoBaseUrl: 'https://addons.mozilla.org/api/v5/',
   sourceDir: ...,
   channel: 'unlisted',
   ...
diff --git a/src/cmd/sign.js b/src/cmd/sign.js
index 1effd157aa..10c4296a84 100644
--- a/src/cmd/sign.js
+++ b/src/cmd/sign.js
@@ -3,6 +3,7 @@ import path from 'path';
 import defaultBuilder from './build.js';
 import { isErrorWithCode, UsageError, WebExtError } from '../errors.js';
 import { prepareArtifactsDir } from '../util/artifacts.js';
+import { AMO_BASE_URL } from '../util/constants.js';
 import { createLogger } from '../util/logger.js';
 import getValidatedManifest, { getManifestId } from '../util/manifest.js';
 import {
@@ -20,7 +21,7 @@ export const uploadUuidFile = '.amo-upload-uuid';
 
 export default function sign(
   {
-    amoBaseUrl,
+    amoBaseUrl = AMO_BASE_URL,
     apiKey,
     apiProxy,
     apiSecret,
diff --git a/src/program.js b/src/program.js
index d76263a3c4..d401d51549 100644
--- a/src/program.js
+++ b/src/program.js
@@ -20,6 +20,7 @@ import {
   loadJSConfigFile as defaultLoadJSConfigFile,
   applyConfigToArgv as defaultApplyConfigToArgv,
 } from './config.js';
+import { AMO_BASE_URL } from './util/constants.js';
 
 const log = createLogger(import.meta.url);
 const envPrefix = 'WEB_EXT';
@@ -27,7 +28,7 @@ const envPrefix = 'WEB_EXT';
 // at build time by scripts/babel-plugin-inline-environment-variables.cjs).
 const defaultGlobalEnv = process.env.WEBEXT_BUILD_ENV || 'development';
 
-export const AMO_BASE_URL = 'https://addons.mozilla.org/api/v5/';
+export { AMO_BASE_URL };
 
 /*
  * The command line program.
diff --git a/src/util/constants.js b/src/util/constants.js
new file mode 100644
index 0000000000..fbcacaaa3b
--- /dev/null
+++ b/src/util/constants.js
@@ -0,0 +1,5 @@
+// Shared constants that both the command line interface and the commands
+// themselves need. Keeping them here avoids importing the CLI program (and
+// its dependencies) from a command module.
+
+export const AMO_BASE_URL = 'https://addons.mozilla.org/api/v5/';
diff --git a/tests/unit/test-cmd/test.sign.js b/tests/unit/test-cmd/test.sign.js
index 21b6d4deae..900c93693f 100644
--- a/tests/unit/test-cmd/test.sign.js
+++ b/tests/unit/test-cmd/test.sign.js
@@ -115,6 +115,17 @@ describe('sign', () => {
       },
     ));
 
+  it('defaults the AMO base URL when it is not passed in', () =>
+    withTempDir(async (tmpDir) => {
+      const stubs = getStubs();
+      const signingConfig = { ...stubs.signingConfig };
+      delete signingConfig.amoBaseUrl;
+      await sign(tmpDir, { ...stubs, signingConfig });
+      sinon.assert.calledWithMatch(stubs.signingOptions.submitAddon, {
+        amoBaseUrl: AMO_BASE_URL,
+      });
+    }));
+
   it('requires a channel for submission API', () =>
     withTempDir(async (tmpDir) => {
       const stubs = getStubs();