diff --git a/h2mux/error.go b/h2mux/error.go
index 4a95bab9..467e99da 100644
--- a/h2mux/error.go
+++ b/h2mux/error.go
@@ -20,10 +20,11 @@ var (
 	ErrUnknownStream       = MuxerProtocolError{"2002 unknown stream", http2.ErrCodeProtocol}
 	ErrInvalidStream       = MuxerProtocolError{"2003 invalid stream", http2.ErrCodeProtocol}
 
-	ErrStreamHeadersSent = MuxerApplicationError{"3000 headers already sent"}
-	ErrConnectionClosed  = MuxerApplicationError{"3001 connection closed"}
-	ErrConnectionDropped = MuxerApplicationError{"3002 connection dropped"}
-	ErrOpenStreamTimeout = MuxerApplicationError{"3003 open stream timeout"}
+	ErrStreamHeadersSent      = MuxerApplicationError{"3000 headers already sent"}
+	ErrConnectionClosed       = MuxerApplicationError{"3001 connection closed"}
+	ErrConnectionDropped      = MuxerApplicationError{"3002 connection dropped"}
+	ErrOpenStreamTimeout      = MuxerApplicationError{"3003 open stream timeout"}
+	ErrResponseHeadersTimeout = MuxerApplicationError{"3004 timeout waiting for initial response headers"}
 
 	ErrClosedStream = MuxerStreamError{"4000 stream closed", http2.ErrCodeStreamClosed}
 )
diff --git a/h2mux/h2mux.go b/h2mux/h2mux.go
index 65034830..2ac07b62 100644
--- a/h2mux/h2mux.go
+++ b/h2mux/h2mux.go
@@ -201,9 +201,9 @@ func Handshake(
 		initialStreamWindow:     m.config.DefaultWindowSize,
 		streamWindowMax:         m.config.MaxWindowSize,
 		streamWriteBufferMaxLen: m.config.StreamWriteBufferMaxLen,
-		r:              m.r,
-		metricsUpdater: m.muxMetricsUpdater,
-		bytesRead:      inBoundCounter,
+		r:                       m.r,
+		metricsUpdater:          m.muxMetricsUpdater,
+		bytesRead:               inBoundCounter,
 	}
 	m.muxWriter = &MuxWriter{
 		f:               m.f,
@@ -406,7 +406,7 @@ func (m *Muxer) OpenStream(ctx context.Context, headers []Header, body io.Reader
 
 	select {
 	case <-ctx.Done():
-		return nil, ErrOpenStreamTimeout
+		return nil, ErrResponseHeadersTimeout
 	case <-m.abortChan:
 		return nil, ErrConnectionClosed
 	case <-stream.responseHeadersReceived: