diff --git a/Cargo.lock b/Cargo.lock
index 3984098be..db7632f3f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -366,10 +366,10 @@ dependencies = [
  "ethcore-util 1.3.0",
  "jsonrpc-core 2.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "parity-minimal-sysui 0.1.0 (git+https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git)",
+ "parity-minimal-sysui 0.2.0 (git+https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git)",
  "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "ws 0.5.0 (git+https://github.com/ethcore/ws-rs.git?branch=stable)",
+ "ws 0.5.0 (git+https://github.com/ethcore/ws-rs.git?branch=testing)",
 ]
 
 [[package]]
@@ -934,8 +934,8 @@ dependencies = [
 
 [[package]]
 name = "parity-minimal-sysui"
-version = "0.1.0"
-source = "git+https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git#cc5ea4bd786982f0509a8d3d5deb4217c659af85"
+version = "0.2.0"
+source = "git+https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git#996c9f3f0ebedc727aecb4ece191154e956ae292"
 
 [[package]]
 name = "phf"
@@ -1448,7 +1448,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 [[package]]
 name = "ws"
 version = "0.5.0"
-source = "git+https://github.com/ethcore/ws-rs.git?branch=stable#abd219709b9dd504a7101d9ba772e0df523fe534"
+source = "git+https://github.com/ethcore/ws-rs.git?branch=testing#4623c51aedaea1ca0ecb34bd1a1aacb651760954"
 dependencies = [
  "httparse 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/signer/Cargo.toml b/signer/Cargo.toml
index 912b10875..e26ffd99e 100644
--- a/signer/Cargo.toml
+++ b/signer/Cargo.toml
@@ -15,10 +15,10 @@ rand = "0.3.14"
 jsonrpc-core = "2.0"
 log = "0.3"
 env_logger = "0.3"
-ws = { git = "https://github.com/ethcore/ws-rs.git", branch = "stable" }
+ws = { git = "https://github.com/ethcore/ws-rs.git", branch = "testing" }
 ethcore-util = { path = "../util" }
 ethcore-rpc = { path = "../rpc" }
-parity-minimal-sysui = { git = "https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git" }
+parity-minimal-sysui = { git = "https://github.com/ethcore/parity-dapps-minimal-sysui-rs.git", version = "0.2.0" }
 
 clippy = { version = "0.0.77", optional = true}
 
diff --git a/signer/src/ws_server/session.rs b/signer/src/ws_server/session.rs
index b635f1524..4b2eb808c 100644
--- a/signer/src/ws_server/session.rs
+++ b/signer/src/ws_server/session.rs
@@ -62,6 +62,19 @@ fn auth_is_valid(codes: &Path, protocols: ws::Result<Vec<&str>>) -> bool {
 	}
 }
 
+fn add_headers(mut response: ws::Response, mime: &str) -> ws::Response {
+	let content_len = format!("{}", response.len());
+	{
+		let mut headers = response.headers_mut();
+		headers.push(("X-Frame-Options".into(), b"SAMEORIGIN".to_vec()));
+		headers.push(("Server".into(), b"Parity/SignerUI".to_vec()));
+		headers.push(("Content-Length".into(), content_len.as_bytes().to_vec()));
+		headers.push(("Content-Type".into(), mime.as_bytes().to_vec()));
+		headers.push(("Connection".into(), b"close".to_vec()));
+	}
+	response
+}
+
 pub struct Session {
 	out: ws::Sender,
 	self_origin: String,
@@ -98,26 +111,13 @@ impl ws::Handler for Session {
 		}
 
 		// Otherwise try to serve a page.
-		sysui::handle(req.resource())
+		Ok(sysui::handle(req.resource())
 			.map_or_else(
-				// return error
-				|| Ok(ws::Response::not_found("Page not found".into())),
+				// return 404 not found
+				|| add_headers(ws::Response::not_found("Not found".into()), "text/plain"),
 				// or serve the file
-				|f| {
-					let content_len = format!("{}", f.content.as_bytes().len());
-					let mut res = ws::Response::ok(f.content.into());
-					{
-						let mut headers = res.headers_mut();
-						headers.push(("Server".into(), b"Parity/SignerUI".to_vec()));
-						headers.push(("Connection".into(), b"Closed".to_vec()));
-						headers.push(("Content-Length".into(), content_len.as_bytes().to_vec()));
-						headers.push(("Content-Type".into(), f.mime.as_bytes().to_vec()));
-						if !f.safe_to_embed {
-							headers.push(("X-Frame-Options".into(), b"SAMEORIGIN".to_vec()));
-						}
-					}
-					Ok(res)
-				})
+				|f| add_headers(ws::Response::ok(f.content.into()), &f.mime)
+			))
 	}
 
 	fn on_message(&mut self, msg: ws::Message) -> ws::Result<()> {