diff --git a/runtime/io.js b/runtime/io.js
index 680640ae1d..ab702a7fa4 100644
--- a/runtime/io.js
+++ b/runtime/io.js
@@ -31,6 +31,10 @@ function caml_sys_close(fd) {
   return 0;
 }
 
+//Provides: MlChanid
+function MlChanid(id){
+  this.id = id
+}
 
 //Provides: caml_sys_open
 //Requires: caml_raise_sys_error
@@ -40,17 +44,18 @@ function caml_sys_close(fd) {
 //Requires: fs_node_supported
 //Requires: caml_sys_fds
 //Requires: caml_sys_open_for_node
+//Requires: MlChanid
 function caml_sys_open_internal(file,idx) {
   var chanid;
   if(idx == undefined){
     idx = caml_sys_fds.length;
-    chanid = Symbol(idx.toString());
+    chanid = new MlChanid(idx);
   }
   else if(caml_sys_fds[idx]){
     chanid = caml_sys_fds[idx].chanid;
   }
   else
-    chanid = Symbol(idx.toString ());
+    chanid = new MlChanid(idx);
   caml_sys_fds[idx] = {file:file, chanid: chanid};
   return idx | 0;
 }
@@ -97,12 +102,13 @@ function caml_sys_open (name, flags, _perms) {
 //Provides: caml_ml_set_channel_name
 //Requires: caml_ml_channels
 function caml_ml_set_channel_name(chanid, name) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   chan.name = name;
   return 0;
 }
 
 //Provides: caml_ml_channels
+//Requires: MlChanid
 function caml_ml_channels_state() {
   this.map = new globalThis.WeakMap ();
   this.opened = new globalThis.Set();
@@ -121,21 +127,7 @@ caml_ml_channels_state.prototype.all = function () {
   return this.opened.values();
 }
 
-var channels_handlers = {
-  get (target, prop, receiver) {
-    if(typeof prop == "symbol"){
-      return target.get(prop);
-    }
-    return globalThis.Reflect.get(...arguments);
-  },
-  set (target, prop, new_val, receiver) {
-    if(typeof prop == "symbol"){
-      target.set(prop, new_val);
-    }
-    return true;
-  }
-}
-var caml_ml_channels = new globalThis.Proxy(new caml_ml_channels_state, channels_handlers);
+var caml_ml_channels = new caml_ml_channels_state;
 
 //Provides: caml_ml_out_channels_list
 //Requires: caml_ml_channels
@@ -144,7 +136,7 @@ function caml_ml_out_channels_list () {
   var l = 0;
   var keys = caml_ml_channels.all();
   for(var k of keys){
-    var chan = caml_ml_channels[k];
+    var chan = caml_ml_channels.get(k);
     if(chan.opened && chan.out) l=[0,k,l];
   }
   return l;
@@ -169,7 +161,7 @@ function caml_ml_open_descriptor_out (fd) {
     buffer:new Uint8Array(65536),
     buffered:buffered
   };
-  caml_ml_channels[chanid] = channel;
+  caml_ml_channels.set(chanid, channel);
   return chanid;
 }
 
@@ -192,7 +184,7 @@ function caml_ml_open_descriptor_in (fd)  {
     buffer:new Uint8Array(65536),
     refill:refill
   };
-  caml_ml_channels[chanid] = channel;
+  caml_ml_channels.set(chanid, channel);
   return chanid;
 }
 
@@ -215,14 +207,14 @@ function caml_ml_open_descriptor_out_with_flags(fd, flags){
 //Requires: caml_ml_channels
 //Alias: win_filedescr_of_channel
 function caml_channel_descriptor(chanid){
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return chan.fd;
 }
 
 //Provides: caml_ml_set_binary_mode
 //Requires: caml_ml_channels
 function caml_ml_set_binary_mode(chanid,mode){
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   chan.file.flags.text = !mode
   chan.file.flags.binary = mode
   return 0;
@@ -232,7 +224,7 @@ function caml_ml_set_binary_mode(chanid,mode){
 //Requires: caml_ml_channels
 //Version: >= 5.2
 function caml_ml_is_binary_mode(chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return chan.file.flags.binary
 }
 
@@ -242,7 +234,7 @@ function caml_ml_is_binary_mode(chanid) {
 //Requires: caml_ml_flush, caml_ml_channels
 //Requires: caml_sys_close
 function caml_ml_close_channel (chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   if(chan.opened) {
     chan.opened = false;
     caml_ml_channels.close(chanid);
@@ -258,21 +250,21 @@ function caml_ml_close_channel (chanid) {
 //Provides: caml_ml_channel_size
 //Requires: caml_ml_channels
 function caml_ml_channel_size(chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return chan.file.length();
 }
 
 //Provides: caml_ml_channel_size_64
 //Requires: caml_int64_of_float,caml_ml_channels
 function caml_ml_channel_size_64(chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return caml_int64_of_float(chan.file.length ());
 }
 
 //Provides: caml_ml_set_channel_output
 //Requires: caml_ml_channels
 function caml_ml_set_channel_output(chanid,f) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   chan.output = (function (s) {f(s)});
   return 0;
 }
@@ -280,7 +272,7 @@ function caml_ml_set_channel_output(chanid,f) {
 //Provides: caml_ml_set_channel_refill
 //Requires: caml_ml_channels
 function caml_ml_set_channel_refill(chanid,f) {
-  caml_ml_channels[chanid].refill = f;
+  caml_ml_channels.get(chanid).refill = f;
   return 0;
 }
 
@@ -329,7 +321,7 @@ function caml_ml_input_bigarray (chanid, b, i, l) {
 //Provides: caml_ml_input_block
 //Requires: caml_refill, caml_ml_channels
 function caml_ml_input_block (chanid, ba, i, l) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   var n = l;
   var avail = chan.buffer_max - chan.buffer_curr;
   if(l <= avail) {
@@ -357,7 +349,7 @@ function caml_ml_input_block (chanid, ba, i, l) {
 //Requires: caml_refill, caml_failwith, caml_raise_end_of_file
 //Requires: caml_marshal_header_size
 function caml_input_value (chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   var header = new Uint8Array(caml_marshal_header_size);
   function block(buffer, offset, n) {
     var r = 0;
@@ -402,7 +394,7 @@ function caml_input_value_to_outside_heap(c) {
 //Requires: caml_raise_end_of_file, caml_array_bound_error
 //Requires: caml_ml_channels, caml_refill
 function caml_ml_input_char (chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   if(chan.buffer_curr >= chan.buffer_max){
     chan.buffer_curr = 0;
     chan.buffer_max = 0;
@@ -419,7 +411,7 @@ function caml_ml_input_char (chanid) {
 //Requires: caml_raise_end_of_file
 //Requires: caml_ml_input_char, caml_ml_channels
 function caml_ml_input_int (chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   var res = 0;
   for(var i = 0; i < 4; i++){
     res = (res << 8) + caml_ml_input_char(chanid) | 0;
@@ -430,7 +422,7 @@ function caml_ml_input_int (chanid) {
 //Provides: caml_seek_in
 //Requires: caml_raise_sys_error, caml_ml_channels
 function caml_seek_in(chanid, pos) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   if (chan.refill != null) caml_raise_sys_error("Illegal seek");
   if(pos >= chan.offset - chan.buffer_max
      && pos <= chan.offset
@@ -460,7 +452,7 @@ function caml_ml_seek_in_64(chanid,pos){
 //Provides: caml_pos_in
 //Requires: caml_ml_channels
 function caml_pos_in(chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return chan.offset - (chan.buffer_max - chan.buffer_curr) | 0;
 }
 
@@ -480,7 +472,7 @@ function caml_ml_pos_in_64(chanid) {
 //Requires: caml_array_bound_error
 //Requires: caml_ml_channels, caml_refill
 function caml_ml_input_scan_line(chanid){
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   var p = chan.buffer_curr;
   do {
     if(p >= chan.buffer_max) {
@@ -507,7 +499,7 @@ function caml_ml_input_scan_line(chanid){
 //Requires: caml_raise_sys_error, caml_ml_channels
 //Requires: caml_subarray_to_jsbytes
 function caml_ml_flush (chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   if(! chan.opened) caml_raise_sys_error("Cannot flush a closed channel");
   if(!chan.buffer || chan.buffer_curr == 0) return 0;
   if(chan.output) {
@@ -526,7 +518,7 @@ function caml_ml_flush (chanid) {
 //Requires: caml_ml_flush,caml_ml_bytes_length
 //Requires: caml_raise_sys_error, caml_ml_channels
 function caml_ml_output_ta(chanid,buffer,offset,len) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   if(! chan.opened) caml_raise_sys_error("Cannot output to a closed channel");
   buffer = buffer.subarray(offset, offset + len);
   if(chan.buffer_curr + buffer.length > chan.buffer.length) {
@@ -611,7 +603,7 @@ function caml_output_value (chanid,v,flags) {
 //Requires: caml_ml_channels, caml_ml_flush
 function caml_seek_out(chanid, pos){
   caml_ml_flush(chanid);
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   chan.offset = pos;
   return 0;
 }
@@ -631,7 +623,7 @@ function caml_ml_seek_out_64(chanid,pos){
 //Provides: caml_pos_out
 //Requires: caml_ml_channels, caml_ml_flush
 function caml_pos_out(chanid) {
-  var chan = caml_ml_channels[chanid];
+  var chan = caml_ml_channels.get(chanid);
   return chan.offset + chan.buffer_curr
 }
 
@@ -660,13 +652,13 @@ function caml_ml_output_int (chanid,i) {
 //Provides: caml_ml_is_buffered
 //Requires: caml_ml_channels
 function caml_ml_is_buffered(chanid) {
-  return caml_ml_channels[chanid].buffered ? 1 : 0
+  return caml_ml_channels.get(chanid).buffered ? 1 : 0
 }
 
 //Provides: caml_ml_set_buffered
 //Requires: caml_ml_channels, caml_ml_flush
 function caml_ml_set_buffered(chanid,v) {
-  caml_ml_channels[chanid].buffered = v;
+  caml_ml_channels.get(chanid).buffered = v;
   if(!v) caml_ml_flush(chanid);
   return 0
 }