diff --git a/server.go b/server.go
index cd26c0619..2ebde5d0a 100644
--- a/server.go
+++ b/server.go
@@ -319,7 +319,9 @@ func (s *Server) processUnaryRPC(t transport.ServerTransport, stream *transport.
 			return err
 		}
 		if traceInfo.tr != nil {
-			traceInfo.tr.LazyLog(&payload{sent: false, msg: req}, true)
+			// TODO: set payload.msg to something that
+			// prints usefully with %s; req is a []byte.
+			traceInfo.tr.LazyLog(&payload{sent: false}, true)
 		}
 		switch pf {
 		case compressionNone: