diff --git a/oauthproxy.go b/oauthproxy.go
index 76fa385..f2c4c7a 100644
--- a/oauthproxy.go
+++ b/oauthproxy.go
@@ -55,7 +55,18 @@ func setProxyUpstreamHostHeader(proxy *httputil.ReverseProxy, target *url.URL) {
 	director := proxy.Director
 	proxy.Director = func(req *http.Request) {
 		director(req)
-		req.Host = target.Host
+		// use RequestURI so that we aren't unescaping encoded slashes in the request path
+		req.URL.Opaque = fmt.Sprintf("//%s%s", target.Host, req.RequestURI)
+		req.URL.RawQuery = ""
+	}
+}
+func setProxyDirector(proxy *httputil.ReverseProxy) {
+	director := proxy.Director
+	proxy.Director = func(req *http.Request) {
+		director(req)
+		// use RequestURI so that we aren't unescaping encoded slashes in the request path
+		req.URL.Opaque = fmt.Sprintf("//%s%s", req.URL.Host, req.RequestURI)
+		req.URL.RawQuery = ""
 	}
 }
 
@@ -70,6 +81,8 @@ func NewOauthProxy(opts *Options, validator func(string) bool) *OauthProxy {
 		proxy := NewReverseProxy(u)
 		if !opts.PassHostHeader {
 			setProxyUpstreamHostHeader(proxy, u)
+		} else {
+			setProxyDirector(proxy)
 		}
 		serveMux.Handle(path, proxy)
 	}
diff --git a/oauthproxy_test.go b/oauthproxy_test.go
index c4e3836..b7969b4 100644
--- a/oauthproxy_test.go
+++ b/oauthproxy_test.go
@@ -35,3 +35,30 @@ func TestNewReverseProxy(t *testing.T) {
 		t.Errorf("got body %q; expected %q", g, e)
 	}
 }
+
+func TestEncodedSlashes(t *testing.T) {
+	var seen string
+	backend := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		seen = r.RequestURI
+	}))
+	defer backend.Close()
+
+	b, _ := url.Parse(backend.URL)
+	proxyHandler := NewReverseProxy(b)
+	setProxyDirector(proxyHandler)
+	frontend := httptest.NewServer(proxyHandler)
+	defer frontend.Close()
+
+	f, _ := url.Parse(frontend.URL)
+	encodedPath := "/a%2Fb/"
+	getReq := &http.Request{URL: &url.URL{Scheme: "http", Host: f.Host, Opaque: encodedPath}}
+	_, err := http.DefaultClient.Do(getReq)
+	if err != nil {
+		t.Fatalf("err %s", err)
+	}
+	expected := backend.URL + encodedPath
+	if seen != expected {
+		t.Errorf("got bad request %q expected %q", seen, expected)
+	}
+}