diff --git a/artiq/coredevice/comm_moninj.py b/artiq/coredevice/comm_moninj.py
index d25da82e8..a6b95983e 100644
--- a/artiq/coredevice/comm_moninj.py
+++ b/artiq/coredevice/comm_moninj.py
@@ -33,14 +33,6 @@ class CommMonInj:
 
         try:
             self._writer.write(b"ARTIQ moninj\n")
-            # get device endian
-            endian = await self._reader.read(1)
-            if endian == b"e":
-                self.endian = "<"
-            elif endian == b"E":
-                self.endian = ">"
-            else:
-                raise IOError("Incorrect reply from device: expected e/E.")
             self._receive_task = asyncio.ensure_future(self._receive_cr())
         except:
             self._writer.close()
@@ -62,19 +54,19 @@ class CommMonInj:
             del self._writer
 
     def monitor_probe(self, enable, channel, probe):
-        packet = struct.pack(self.endian + "bblb", 0, enable, channel, probe)
+        packet = struct.pack("<bblb", 0, enable, channel, probe)
         self._writer.write(packet)
 
     def monitor_injection(self, enable, channel, overrd):
-        packet = struct.pack(self.endian + "bblb", 3, enable, channel, overrd)
+        packet = struct.pack("<bblb", 3, enable, channel, overrd)
         self._writer.write(packet)
 
     def inject(self, channel, override, value):
-        packet = struct.pack(self.endian + "blbb", 1, channel, override, value)
+        packet = struct.pack("<blbb", 1, channel, override, value)
         self._writer.write(packet)
 
     def get_injection_status(self, channel, override):
-        packet = struct.pack(self.endian + "blb", 2, channel, override)
+        packet = struct.pack("<blb", 2, channel, override)
         self._writer.write(packet)
 
     async def _receive_cr(self):
@@ -85,12 +77,11 @@ class CommMonInj:
                     return
                 if ty == b"\x00":
                     payload = await self._reader.readexactly(13)
-                    channel, probe, value = struct.unpack(self.endian + "lbq", payload)
+                    channel, probe, value = struct.unpack("<lbq", payload)
                     self.monitor_cb(channel, probe, value)
                 elif ty == b"\x01":
                     payload = await self._reader.readexactly(6)
-                    channel, override, value = struct.unpack(
-                        self.endian + "lbb", payload)
+                    channel, override, value = struct.unpack("<lbb", payload)
                     self.injection_status_cb(channel, override, value)
                 else:
                     raise ValueError("Unknown packet type", ty)
diff --git a/artiq/firmware/runtime/moninj.rs b/artiq/firmware/runtime/moninj.rs
index 76a209f63..61b6ddf15 100644
--- a/artiq/firmware/runtime/moninj.rs
+++ b/artiq/firmware/runtime/moninj.rs
@@ -123,7 +123,6 @@ fn connection_worker(io: &Io, _aux_mutex: &Mutex, _routing_table: &drtio_routing
     let mut next_check = 0;
 
     read_magic(&mut stream)?;
-    stream.write_all("e".as_bytes())?;
     info!("new connection from {}", stream.remote_endpoint());
 
     loop {
diff --git a/artiq/frontend/aqctl_moninj_proxy.py b/artiq/frontend/aqctl_moninj_proxy.py
index 12767891c..0ce317fba 100755
--- a/artiq/frontend/aqctl_moninj_proxy.py
+++ b/artiq/frontend/aqctl_moninj_proxy.py
@@ -169,7 +169,6 @@ class ProxyServer(AsyncioServer):
         if line != b"ARTIQ moninj\n":
             logger.error("incorrect magic")
             return
-        writer.write(b"e")
         await ProxyConnection(self.monitor_mux, reader, writer).handle()