diff --git a/source/vibe/http/proxy.d b/source/vibe/http/proxy.d
index 6178711..274aaad 100644
--- a/source/vibe/http/proxy.d
+++ b/source/vibe/http/proxy.d
@@ -181,7 +181,7 @@ HTTPServerRequestDelegateS proxyRequest(HTTPProxySettings settings)
 			if ("Content-Length" !in cres.headers && "Transfer-Encoding" !in cres.headers || req.method == HTTPMethod.HEAD) {
 				foreach (key, ref value; cres.headers.byKeyValue)
 					if (icmp2(key, "Connection") != 0)
-						res.headers[key] = value;
+						res.headers.addField(key,value);
 				res.writeVoidBody();
 				return;
 			}
@@ -192,7 +192,7 @@ HTTPServerRequestDelegateS proxyRequest(HTTPProxySettings settings)
 				// copy all headers that may pass from upstream to client
 				foreach (n, ref v; cres.headers.byKeyValue)
 					if (n !in non_forward_headers_map)
-						res.headers[n] = v;
+						res.headers.addField(n,v);
 
 				if ("Transfer-Encoding" in res.headers) res.headers.remove("Transfer-Encoding");
 				auto content = cres.bodyReader.readAll(1024*1024);
@@ -207,7 +207,7 @@ HTTPServerRequestDelegateS proxyRequest(HTTPProxySettings settings)
 				if ("Content-Encoding" in res.headers) res.headers.remove("Content-Encoding");
 				foreach (key, ref value; cres.headers.byKeyValue)
 					if (icmp2(key, "Connection") != 0)
-						res.headers[key] = value;
+						res.headers.addField(key,value);
 				auto size = cres.headers["Content-Length"].to!size_t();
 				if (res.isHeadResponse) res.writeVoidBody();
 				else cres.readRawBody((scope InterfaceProxy!InputStream reader) { res.writeRawBody(reader, size); });
@@ -219,7 +219,7 @@ HTTPServerRequestDelegateS proxyRequest(HTTPProxySettings settings)
 			// copy all headers that may pass from upstream to client
 			foreach (n, ref v; cres.headers.byKeyValue)
 				if (n !in non_forward_headers_map)
-					res.headers[n] = v;
+					res.headers.addField(n,v);
 			if (res.isHeadResponse) res.writeVoidBody();
 			else cres.bodyReader.pipe(res.bodyWriter);
 		}
diff --git a/tests/vibe.http.proxy.copyHeaders/dub.sdl b/tests/vibe.http.proxy.copyHeaders/dub.sdl
new file mode 100644
index 0000000..ee99ce9
--- /dev/null
+++ b/tests/vibe.http.proxy.copyHeaders/dub.sdl
@@ -0,0 +1,3 @@
+name "tests"
+description "proxy tests"
+dependency "vibe-http" path="../../"
diff --git a/tests/vibe.http.proxy.copyHeaders/source/app.d b/tests/vibe.http.proxy.copyHeaders/source/app.d
new file mode 100644
index 0000000..91452fb
--- /dev/null
+++ b/tests/vibe.http.proxy.copyHeaders/source/app.d
@@ -0,0 +1,40 @@
+import vibe.core.core;
+import vibe.core.log;
+import vibe.http.client;
+import vibe.http.server;
+import vibe.http.proxy;
+import vibe.http.router;
+import vibe.stream.operations : readAllUTF8;
+import std.algorithm : find;
+import std.range.primitives : front;
+import std.socket : AddressFamily;
+import std.stdio;
+
+void main()
+{
+	auto settings = new HTTPServerSettings;
+	settings.port = 0;
+        settings.bindAddresses = ["127.0.0.1"];
+
+	immutable serverAddr = listenHTTP(settings, (scope req, scope res) {
+		res.headers.addField("X","Y");
+		res.headers.addField("X","Z");
+		res.writeBody("Hello world.");
+	}).bindAddresses.find!(addr => addr.family == AddressFamily.INET).front;
+	
+	auto router = new URLRouter;
+	router.get("/", reverseProxyRequest(serverAddr.toAddressString,serverAddr.port));
+	immutable proxyAddr = listenHTTP(settings, router).bindAddresses.find!(addr => addr.family == AddressFamily.INET).front;
+
+	auto res = requestHTTP("http://" ~ proxyAddr.toString);
+	assert(res.statusCode == HTTPStatus.ok);
+	bool hadY;
+	bool hadZ;
+	foreach (k, v; res.headers.byKeyValue) {
+		if ((k == "X") && (v == "Y")) hadY = true;
+		if ((k == "X") && (v == "Z")) hadZ = true;
+	}
+	assert(hadZ);
+	assert(hadY);
+	assert(res.bodyReader.readAllUTF8 == "Hello world.");
+}