diff --git a/lib/configproxy.js b/lib/configproxy.js
index 46652a51..7967527f 100644
--- a/lib/configproxy.js
+++ b/lib/configproxy.js
@@ -392,19 +392,19 @@ export class ConfigurableProxy extends EventEmitter {
     var proxyOptions = { target };
 
     if (target.protocol.startsWith("unix")) {
+      // No need for agents for unix sockets
+      // No support for https for unix sockets
       proxyOptions.secure = false;
       proxyOptions.target.socketPath = decodeURIComponent(target.host);
       proxyOptions.target.pathname = (target.pathname ? target.pathname + "/" : "") + reqUrl;
+    } else if (target.protocol.startsWith("https")) {
+      proxyOptions.secure = true;
+      proxyOptions.agent = this.httpsAgent;
+    } else if (target.protocol.startsWith("http")) {
+      proxyOptions.secure = false;
+      proxyOptions.agent = this.httpAgent;
     } else {
-      // No need for agents for unix sockets
-      // No support for https for unix sockets
-      proxyOptions.secure = target.protocol.slice(-2) === "s:";
-
-      if (proxyOptions.secure) {
-        proxyOptions.agent = this.httpsAgent;
-      } else {
-        proxyOptions.agent = this.httpAgent;
-      }
+      throw new Error(`Unexpected protocol ${target.protocol}`);
     }
 
     if (proxyOptions.secure && this.options.clientSsl) {
diff --git a/lib/testutil.js b/lib/testutil.js
index 4216879a..088e6dbe 100644
--- a/lib/testutil.js
+++ b/lib/testutil.js
@@ -10,14 +10,16 @@ var servers = [];
 
 // TODO: make this an options dict
 export function addTarget(proxy, path, port, websocket, targetPath, sslOptions, unixSocketPath) {
-  var proto = sslOptions ? "https" : "http";
+  var proto;
   var listenTarget;
   var target;
 
   if (unixSocketPath) {
     listenTarget = decodeURIComponent(unixSocketPath);
+    proto = "http";
     target = "unix+" + proto + "://" + unixSocketPath;
   } else {
+    proto = sslOptions ? "https" : "http";
     target = proto + "://" + "127.0.0.1:" + port;
     listenTarget = port;
   }