diff --git a/frontend/ui/message/streammessagequeue.lua b/frontend/ui/message/streammessagequeue.lua
index 4a19d3dbf..4b6f8b1ce 100644
--- a/frontend/ui/message/streammessagequeue.lua
+++ b/frontend/ui/message/streammessagequeue.lua
@@ -22,7 +22,7 @@ function StreamMessageQueue:start()
     if rc ~= 0 then
         error("cannot connect to " .. endpoint)
     end
-    local id_size = ffi.new("size_t[1]", 256)
+    local id_size = ffi.new("unsigned int[1]", 256)
     local buffer = ffi.new("uint8_t[?]", id_size[0])
     -- @todo: check return of zmq_getsockopt
     zmq.zmq_getsockopt(self.socket, C.ZMQ_IDENTITY, buffer, id_size)