diff --git a/emcc.c b/emcc.c
index 31aedbd..25f5282 100644
--- a/emcc.c
+++ b/emcc.c
@@ -99,6 +99,8 @@ extern void js_dialog_launch(void);
 extern void js_dialog_cleanup(void);
 extern void js_focus_canvas(void);
 
+extern bool js_savefile_read(void *buf, int len);
+
 /*
  * These functions are called from JavaScript, so their prototypes
  * need to be kept in sync with emccpre.js.
@@ -112,7 +114,7 @@ void timer_callback(double tplus);
 void command(int n);
 char *get_save_file(void);
 void free_save_file(char *buffer);
-void load_game(const char *buffer, int len);
+void load_game(void);
 void dlg_return_sval(int index, const char *val);
 void dlg_return_ival(int index, int val);
 void resize_puzzle(int w, int h);
@@ -904,23 +906,18 @@ struct savefile_read_ctx {
 
 static bool savefile_read(void *vctx, void *buf, int len)
 {
-    struct savefile_read_ctx *ctx = (struct savefile_read_ctx *)vctx;
-    if (ctx->len_remaining < len)
-        return false;
-    memcpy(buf, ctx->buffer, len);
-    ctx->len_remaining -= len;
-    ctx->buffer += len;
-    return true;
+    return js_savefile_read(buf, len);
 }
 
-void load_game(const char *buffer, int len)
+void load_game()
 {
-    struct savefile_read_ctx ctx;
     const char *err;
 
-    ctx.buffer = buffer;
-    ctx.len_remaining = len;
-    err = midend_deserialise(me, savefile_read, &ctx);
+    /*
+     * savefile_read_callback in JavaScript was set up by our caller
+     * as a closure that knows what file we're loading.
+     */
+    err = midend_deserialise(me, savefile_read, NULL);
 
     if (err) {
         js_error_box(err);
diff --git a/emcclib.js b/emcclib.js
index 07cbf3b..80d17b9 100644
--- a/emcclib.js
+++ b/emcclib.js
@@ -783,5 +783,14 @@ mergeInto(LibraryManager.library, {
      */
     js_focus_canvas: function() {
         onscreen_canvas.focus();
+    },
+
+    /*
+     * bool js_savefile_read(void *buf, int len);
+     *
+     * Read len bytes from the save file that we're currently loading.
+     */
+    js_savefile_read: function(buf, len) {
+        return savefile_read_callback(buf, len);
     }
 });
diff --git a/emccpre.js b/emccpre.js
index 2637bcb..837f815 100644
--- a/emccpre.js
+++ b/emccpre.js
@@ -135,6 +135,12 @@ var dlg_return_funcs = null;
 // pass back the final value in each dialog control.
 var dlg_return_sval, dlg_return_ival;
 
+// Callback for reading from a savefile.  This will be filled in with
+// a suitable closure by the JS loading code and called by
+// js_savefile_read().  This assumes that only one file can be in the
+// process of loading at a time.
+var savefile_read_callback;
+
 // The <ul> object implementing the game-type drop-down, and a list of
 // the sub-lists inside it. Used by js_add_preset().
 var gametypelist = document.getElementById("gametype");
@@ -423,7 +429,7 @@ function initPuzzle() {
     // 'number' is used for C pointers
     var get_save_file = Module.cwrap('get_save_file', 'number', []);
     var free_save_file = Module.cwrap('free_save_file', 'void', ['number']);
-    var load_game = Module.cwrap('load_game', 'void', ['array', 'number']);
+    var load_game = Module.cwrap('load_game', 'void', []);
 
     if (save_button) save_button.onclick = function(event) {
         if (dlg_dimmer === null) {
@@ -457,8 +463,17 @@ function initPuzzle() {
                     var file = input.files.item(0);
                     var reader = new FileReader();
                     reader.addEventListener("loadend", function() {
-                        var array = new Uint8Array(reader.result);
-                        load_game(array, array.length);
+                        var pos = 0;
+                        savefile_read_callback = function(buf, len) {
+                            if (pos + len > reader.result.byteLength)
+                                return false;
+                            writeArrayToMemory(
+                                new Int8Array(reader.result, pos, len), buf);
+                            pos += len;
+                            return true;
+                        }
+                        load_game();
+                        savefile_read_callback = null;
                     });
                     reader.readAsArrayBuffer(file);
                 }