diff --git a/environ/proxy.go b/environ/proxy.go
index c779eac..4668c7d 100644
--- a/environ/proxy.go
+++ b/environ/proxy.go
@@ -23,6 +23,10 @@ func Proxy() map[string]string {
 		environ["https_proxy"] = value
 		environ["HTTPS_PROXY"] = value
 	}
+	if value := envAnyCase("all_proxy"); value != "" {
+		environ["all_proxy"] = value
+		environ["ALL_PROXY"] = value
+	}
 	return environ
 }
 
diff --git a/environ/proxy_test.go b/environ/proxy_test.go
index 513ef01..44f9dc0 100644
--- a/environ/proxy_test.go
+++ b/environ/proxy_test.go
@@ -24,6 +24,8 @@ func TestProxy(t *testing.T) {
 			return "http://dummy.http.proxy"
 		case "https_proxy":
 			return "http://dummy.https.proxy"
+		case "all_proxy":
+			return "http://dummy.https.proxy"
 		default:
 			return ""
 		}
@@ -36,6 +38,8 @@ func TestProxy(t *testing.T) {
 		"HTTP_PROXY":  "http://dummy.http.proxy",
 		"https_proxy": "http://dummy.https.proxy",
 		"HTTPS_PROXY": "http://dummy.https.proxy",
+		"all_proxy":   "http://dummy.https.proxy",
+		"ALL_PROXY":   "http://dummy.https.proxy",
 	}
 	b := Proxy()
 	if diff := cmp.Diff(a, b); diff != "" {