diff --git a/__tests__/server/utils/stateConfig.spec.js b/__tests__/server/utils/stateConfig.spec.js
index 0e347497..9fe2a7d2 100644
--- a/__tests__/server/utils/stateConfig.spec.js
+++ b/__tests__/server/utils/stateConfig.spec.js
@@ -195,6 +195,22 @@ describe('stateConfig methods', () => {
         expect(getClientStateConfig()).toMatchSnapshot();
         expect(getServerStateConfig()).toMatchSnapshot();
       });
+      it('dev endpoint should not have doubled slash in path', () => {
+        process.env.NODE_ENV = 'development';
+        // eslint-disable-next-line unicorn/import-index, import/no-unresolved
+        require('fake/path/.dev/endpoints/index.js').mockImplementation(() => ({
+          leadingSlashApiUrl: {
+            devProxyPath: '/leading-slash-api',
+            destination: 'https://intranet-origin-dev.example.com/some-other-api/v1',
+          },
+        }));
+        ({
+          setStateConfig,
+          getClientStateConfig,
+          getServerStateConfig,
+        } = require('../../../src/server/utils/stateConfig'));
+        expect(getClientStateConfig().leadingSlashApiUrl).toEqual('http://127.0.0.1:3002/leading-slash-api');
+      });
     });
     describe('with env vars', () => {
       it('should parse string undefined as js undefined', () => {
diff --git a/src/server/utils/stateConfig.js b/src/server/utils/stateConfig.js
index 7f9daa17..a446f7ad 100644
--- a/src/server/utils/stateConfig.js
+++ b/src/server/utils/stateConfig.js
@@ -17,6 +17,7 @@
 import ip from 'ip';
 import fs from 'fs';
 import path from 'path';
+import url from 'url';
 import envVarAllowList from './envVarAllowList';
 import snakeCaseToCamelCase from './snakeCaseToCamelCase';
 
@@ -76,7 +77,12 @@ if (process.env.NODE_ENV === 'development' && fs.existsSync(pathToDevEndpoints))
   // eslint-disable-next-line global-require,import/no-dynamic-require
   const devEndpoints = require(pathToDevEndpoints)();
   Object.entries(devEndpoints).forEach(([configName, { devProxyPath }]) => {
-    const value = `http://${ipAddress}:${SERVICES_PORT}/${devProxyPath}`;
+    const value = url.format({
+      protocol: 'http',
+      hostname: ipAddress,
+      port: SERVICES_PORT,
+      pathname: devProxyPath,
+    });
     stateConfigFromDevEndpoints[configName] = value;
   });
 }