diff --git a/src/h2load.cc b/src/h2load.cc
index 1704f26c..5daff7b0 100644
--- a/src/h2load.cc
+++ b/src/h2load.cc
@@ -204,9 +204,6 @@ int Client::connect() {
 
   writefn = &Client::connected;
 
-  on_readfn = &Client::on_read;
-  on_writefn = &Client::on_write;
-
   ev_io_set(&rev, fd, EV_READ);
   ev_io_set(&wev, fd, EV_WRITE);
 
diff --git a/src/h2load.h b/src/h2load.h
index a7b8f67d..6a837c1a 100644
--- a/src/h2load.h
+++ b/src/h2load.h
@@ -166,8 +166,6 @@ struct Client {
   ev_io wev;
   ev_io rev;
   std::function<int(Client &)> readfn, writefn;
-  std::function<int(Client &, const uint8_t *, size_t)> on_readfn;
-  std::function<int(Client &)> on_writefn;
   Worker *worker;
   SSL *ssl;
   addrinfo *next_addr;
@@ -198,6 +196,7 @@ struct Client {
   int do_read();
   int do_write();
 
+  // low-level I/O callback functions called by do_read/do_write
   int connected();
   int read_clear();
   int write_clear();