diff --git a/build/lifecycle_test.go b/build/lifecycle_test.go
index 0f04ceb29..5074089d1 100644
--- a/build/lifecycle_test.go
+++ b/build/lifecycle_test.go
@@ -145,6 +145,9 @@ func testLifecycle(t *testing.T, when spec.G, it spec.S) {
 				h.AssertContains(t, outBuf.String(), "HTTP_PROXY=some-http-proxy")
 				h.AssertContains(t, outBuf.String(), "HTTPS_PROXY=some-https-proxy")
 				h.AssertContains(t, outBuf.String(), "NO_PROXY=some-no-proxy")
+				h.AssertContains(t, outBuf.String(), "http_proxy=some-http-proxy")
+				h.AssertContains(t, outBuf.String(), "https_proxy=some-https-proxy")
+				h.AssertContains(t, outBuf.String(), "no_proxy=some-no-proxy")
 			})
 
 			when("#WithArgs", func() {
diff --git a/build/phase.go b/build/phase.go
index bc09dbf8f..586cd152a 100644
--- a/build/phase.go
+++ b/build/phase.go
@@ -55,12 +55,15 @@ func (l *Lifecycle) NewPhase(name string, ops ...func(*Phase) (*Phase, error)) (
 
 	if l.httpProxy != "" {
 		phase.ctrConf.Env = append(phase.ctrConf.Env, "HTTP_PROXY="+l.httpProxy)
+		phase.ctrConf.Env = append(phase.ctrConf.Env, "http_proxy="+l.httpProxy)
 	}
 	if l.httpsProxy != "" {
 		phase.ctrConf.Env = append(phase.ctrConf.Env, "HTTPS_PROXY="+l.httpsProxy)
+		phase.ctrConf.Env = append(phase.ctrConf.Env, "https_proxy="+l.httpsProxy)
 	}
 	if l.noProxy != "" {
 		phase.ctrConf.Env = append(phase.ctrConf.Env, "NO_PROXY="+l.noProxy)
+		phase.ctrConf.Env = append(phase.ctrConf.Env, "no_proxy="+l.noProxy)
 	}
 
 	var err error
diff --git a/build/testdata/fake-lifecycle/phase.go b/build/testdata/fake-lifecycle/phase.go
index 1018c354a..f6bee7d95 100644
--- a/build/testdata/fake-lifecycle/phase.go
+++ b/build/testdata/fake-lifecycle/phase.go
@@ -139,6 +139,9 @@ func testProxy() {
 	fmt.Println("HTTP_PROXY="+os.Getenv("HTTP_PROXY"))
 	fmt.Println("HTTPS_PROXY="+os.Getenv("HTTPS_PROXY"))
 	fmt.Println("NO_PROXY="+os.Getenv("NO_PROXY"))
+	fmt.Println("http_proxy="+os.Getenv("http_proxy"))
+	fmt.Println("https_proxy="+os.Getenv("https_proxy"))
+	fmt.Println("no_proxy="+os.Getenv("no_proxy"))
 }
 
 func testBinds() {