diff --git a/rolo/proxy.py b/rolo/proxy.py
index c5d125c..b704951 100644
--- a/rolo/proxy.py
+++ b/rolo/proxy.py
@@ -75,6 +75,9 @@ def forward(
             else:
                 headers["X-Forwarded-For"] = f"{client_ip}"
 
+        if "X-Forwarded-Proto" not in request.headers and "X-Forwarded-Proto" not in headers:
+            headers["X-Forwarded-Proto"] = f"{request.scheme}"
+
         if forward_path is None:
             forward_path = get_raw_path(request)
         if forward_path:
diff --git a/tests/test_proxy.py b/tests/test_proxy.py
index 62a09e0..89e83f2 100644
--- a/tests/test_proxy.py
+++ b/tests/test_proxy.py
@@ -111,7 +111,7 @@ def test_get_with_different_base_url_plain_rule(self, router_server, httpserver:
         assert response.ok
         assert response.text == "ok/bar/"  # it's calling /bar/ because it's part of the root URL
 
-    def test_xff_header(self, router_server, httpserver: HTTPServer):
+    def test_x_forwarded_for_header(self, router_server, httpserver: HTTPServer):
         router, proxy = router_server
         backend = httpserver
 
@@ -133,6 +133,28 @@ def _echo_headers(request):
         headers = response.json()
         assert headers["X-Forwarded-For"] == "127.0.0.2, 127.0.0.1"
 
+    def test_x_forwarded_proto_header(self, router_server, httpserver: HTTPServer):
+        router, proxy = router_server
+        backend = httpserver
+
+        def _echo_headers(request):
+            return Response(json.dumps(dict(request.headers)), mimetype="application/json")
+
+        backend.expect_request("/echo").respond_with_handler(_echo_headers)
+
+        router.add("/<path:path>", ProxyHandler(backend.url_for("/")))
+
+        response = requests.get(proxy.url + "/echo")
+        assert response.ok
+        headers = response.json()
+        assert headers["X-Forwarded-Proto"] == "http"
+
+        # Any existing X-Forwarded-Proto header should not be overwritten
+        response = requests.get(proxy.url + "/echo", headers={"X-Forwarded-Proto": "https"})
+        assert response.ok
+        headers = response.json()
+        assert headers["X-Forwarded-Proto"] == "https"
+
     def test_post_form_data_with_query_args(self, router_server, httpserver: HTTPServer):
         router, proxy = router_server
         backend = httpserver