diff --git a/tests/debugclient.nim b/tests/debugclient.nim
index 1e1f5b1..7065035 100644
--- a/tests/debugclient.nim
+++ b/tests/debugclient.nim
@@ -7,7 +7,8 @@ proc rawCall*(self: RpcClient, name: string,
   let id = $self.nextId
   self.nextId.inc
   debug "Sending message", msg = msg
-  let res = await self.transp.write(msg & "\c\l")
+  var s = msg & "\c\l"
+  let res = await self.transp.write(s)
   debug "Receiving length assert", value = res, length = len(msg), lengthDifferent = res != len(msg)
 
   # completed by processMessage.