diff --git a/lib/manager/pip_requirements/extract.spec.ts b/lib/manager/pip_requirements/extract.spec.ts
index 1619e3b98c..271443a0fa 100644
--- a/lib/manager/pip_requirements/extract.spec.ts
+++ b/lib/manager/pip_requirements/extract.spec.ts
@@ -45,8 +45,14 @@ describe('lib/manager/pip_requirements/extract', () => {
   });
   describe('extractPackageFile()', () => {
     let config;
+    const OLD_ENV = process.env;
     beforeEach(() => {
       config = { registryUrls: ['AnExistingDefaultUrl'] };
+      process.env = { ...OLD_ENV };
+      delete process.env.PIP_INDEX_URL;
+    });
+    afterEach(() => {
+      process.env = OLD_ENV;
     });
     it('returns null for empty', () => {
       expect(
diff --git a/lib/manager/pip_requirements/extract.ts b/lib/manager/pip_requirements/extract.ts
index 0ec21b5437..448d90b4d6 100644
--- a/lib/manager/pip_requirements/extract.ts
+++ b/lib/manager/pip_requirements/extract.ts
@@ -44,7 +44,7 @@ export function extractPackageFile(
     registryUrls = registryUrls.concat(config.registryUrls);
   } else if (extraUrls.length) {
     // Use default registry first if extra URLs are present and index URL is not
-    registryUrls.push('https://pypi.org/pypi/');
+    registryUrls.push(process.env.PIP_INDEX_URL || 'https://pypi.org/pypi/');
   }
   registryUrls = registryUrls.concat(extraUrls);
 
diff --git a/lib/manager/poetry/extract.spec.ts b/lib/manager/poetry/extract.spec.ts
index f0b812696e..b91ca40050 100644
--- a/lib/manager/poetry/extract.spec.ts
+++ b/lib/manager/poetry/extract.spec.ts
@@ -49,8 +49,14 @@ const pyproject9toml = readFileSync(
 describe('lib/manager/poetry/extract', () => {
   describe('extractPackageFile()', () => {
     let filename: string;
+    const OLD_ENV = process.env;
     beforeEach(() => {
       filename = '';
+      process.env = { ...OLD_ENV };
+      delete process.env.PIP_INDEX_URL;
+    });
+    afterEach(() => {
+      process.env = OLD_ENV;
     });
     it('returns null for empty', () => {
       expect(extractPackageFile('nothing here', filename)).toBeNull();
diff --git a/lib/manager/poetry/extract.ts b/lib/manager/poetry/extract.ts
index eff864a62c..fb2bc14853 100644
--- a/lib/manager/poetry/extract.ts
+++ b/lib/manager/poetry/extract.ts
@@ -82,7 +82,7 @@ function extractRegistries(pyprojectfile: PoetryFile): string[] {
       registryUrls.add(source.url);
     }
   }
-  registryUrls.add('https://pypi.org/pypi/');
+  registryUrls.add(process.env.PIP_INDEX_URL || 'https://pypi.org/pypi/');
 
   return Array.from(registryUrls);
 }