diff --git a/lib/proxy.spec.ts b/lib/proxy.spec.ts
index 408b9a275d51715c0b5672249d0ce7b60a5d9ab1..c999ed909f9d3d7d3836ada0a3e98e92a96ea19e 100644
--- a/lib/proxy.spec.ts
+++ b/lib/proxy.spec.ts
@@ -7,9 +7,7 @@ describe('proxy', () => {
 
   beforeEach(() => {
     delete process.env.HTTP_PROXY;
-    delete process.env.http_proxy;
     delete process.env.HTTPS_PROXY;
-    delete process.env.https_proxy;
     delete process.env.NO_PROXY;
     delete process.env.no_proxy;
   });
@@ -19,35 +17,11 @@ describe('proxy', () => {
     bootstrap();
     expect(hasProxy()).toBeTrue();
   });
-  it('copies upper case HTTP_PROXY to http_proxy', () => {
-    process.env.HTTP_PROXY = httpProxy;
-    bootstrap();
-    expect(hasProxy()).toBeTrue();
-    expect(process.env.HTTP_PROXY).toBeDefined();
-    expect(process.env.http_proxy).toBeDefined();
-
-    expect(process.env.HTTPS_PROXY).toBeUndefined();
-    expect(process.env.https_proxy).toBeUndefined();
-    expect(process.env.NO_PROXY).toBeUndefined();
-    expect(process.env.no_proxy).toBeUndefined();
-  });
   it('respects HTTPS_PROXY', () => {
     process.env.HTTPS_PROXY = httpsProxy;
     bootstrap();
     expect(hasProxy()).toBeTrue();
   });
-  it('copies upper case HTTPS_PROXY to https_proxy', () => {
-    process.env.HTTPS_PROXY = httpsProxy;
-    bootstrap();
-    expect(hasProxy()).toBeTrue();
-    expect(process.env.HTTPS_PROXY).toBeDefined();
-    expect(process.env.https_proxy).toBeDefined();
-
-    expect(process.env.HTTP_PROXY).toBeUndefined();
-    expect(process.env.http_proxy).toBeUndefined();
-    expect(process.env.NO_PROXY).toBeUndefined();
-    expect(process.env.no_proxy).toBeUndefined();
-  });
   it('does nothing', () => {
     process.env.no_proxy = noProxy;
     bootstrap();
diff --git a/lib/proxy.ts b/lib/proxy.ts
index cb577b55c3f2adaadddc274cb8ee5d43f9d622e5..a1f7ca6d61a8a835877b97e0229509de0eaccf99 100644
--- a/lib/proxy.ts
+++ b/lib/proxy.ts
@@ -14,10 +14,6 @@ export function bootstrap(): void {
     ) {
       process.env[envVar] = process.env[envVar.toLowerCase()];
     }
-
-    if (process.env[envVar]) {
-      process.env[envVar.toLowerCase()] = process.env[envVar];
-    }
   });
 
   if (
diff --git a/lib/util/exec/env.ts b/lib/util/exec/env.ts
index 480338560ec826e584d7cf3591c6427f35a3d443..faffd61bf8152631c87d651775975781671f743b 100644
--- a/lib/util/exec/env.ts
+++ b/lib/util/exec/env.ts
@@ -4,9 +4,6 @@ const basicEnvVars = [
   'HTTP_PROXY',
   'HTTPS_PROXY',
   'NO_PROXY',
-  'http_proxy',
-  'https_proxy',
-  'no_proxy',
   'HOME',
   'PATH',
   'LC_ALL',