diff --git a/www/common/common-util.js b/www/common/common-util.js
index 3419b5160..22b374ad3 100644
--- a/www/common/common-util.js
+++ b/www/common/common-util.js
@@ -616,8 +616,30 @@
                      getColor().toString(16);
     };
 
+    /*  Chrome 92 dropped support for SharedArrayBuffer in cross-origin contexts
+        where window.crossOriginIsolated is false.
+
+        Their blog (https://blog.chromium.org/2021/02/restriction-on-sharedarraybuffers.html)
+        isn't clear about why they're doing this, but since it's related to site-isolation
+        it seems they're trying to do vague security things.
+
+        In any case, there seems to be a workaround where you can still create them
+        by using `new WebAssembly.Memory({shared: true, ...})` instead of `new SharedArrayBuffer`.
+
+        This seems unreliable, but it's better than not being able to export, since
+        we actively rely on postMessage between iframes and therefore can't afford
+        to opt for full isolation.
+    */
+    var supportsSharedArrayBuffers = function () {
+        try {
+            return Object.prototype.toString.call(new window.WebAssembly.Memory({shared: true, initial: 0, maximum: 0}).buffer) === '[object SharedArrayBuffer]';
+        } catch (err) {
+            console.error(err);
+        }
+        return false;
+    };
     Util.supportsWasm = function () {
-        return !(typeof(Atomics) === "undefined" || typeof (SharedArrayBuffer) === "undefined" || typeof(WebAssembly) === 'undefined');
+        return !(typeof(Atomics) === "undefined" || !supportsSharedArrayBuffers() || typeof(WebAssembly) === 'undefined');
     };
 
     if (typeof(module) !== 'undefined' && module.exports) {
diff --git a/www/common/make-backup.js b/www/common/make-backup.js
index 4805aaba5..a80663677 100644
--- a/www/common/make-backup.js
+++ b/www/common/make-backup.js
@@ -41,8 +41,8 @@ define([
         }
         var path = '/' + type + '/export.js';
         require([path], function (Exporter) {
-            Exporter.main(json, function (data) {
-                result.ext = Exporter.ext || '';
+            Exporter.main(json, function (data, _ext) {
+                result.ext = _ext || Exporter.ext || '';
                 result.data = data;
                 cb(result);
             }, null, ctx.sframeChan, padData);
diff --git a/www/common/onlyoffice/inner.js b/www/common/onlyoffice/inner.js
index 9e31fa998..1ea9f5000 100644
--- a/www/common/onlyoffice/inner.js
+++ b/www/common/onlyoffice/inner.js
@@ -74,34 +74,6 @@ define([
         return JSONSortify(obj);
     };
 
-    /*  Chrome 92 dropped support for SharedArrayBuffer in cross-origin contexts
-        where window.crossOriginIsolated is false.
-
-        Their blog (https://blog.chromium.org/2021/02/restriction-on-sharedarraybuffers.html)
-        isn't clear about why they're doing this, but since it's related to site-isolation
-        it seems they're trying to do vague security things.
-
-        In any case, there seems to be a workaround where you can still create them
-        by using `new WebAssembly.Memory({shared: true, ...})` instead of `new SharedArrayBuffer`.
-
-        This seems unreliable, but it's better than not being able to export, since
-        we actively rely on postMessage between iframes and therefore can't afford
-        to opt for full isolation.
-    */
-    var supportsSharedArrayBuffers = function () {
-        try {
-            return Object.prototype.toString.call(new window.WebAssembly.Memory({shared: true, initial: 0, maximum: 0}).buffer) === '[object SharedArrayBuffer]';
-        } catch (err) {
-            console.error(err);
-        }
-        return false;
-    };
-
-    var supportsXLSX = function () {
-        return !(typeof(Atomics) === "undefined" || !supportsSharedArrayBuffers() /* || typeof (SharedArrayBuffer) === "undefined" */ || typeof(WebAssembly) === 'undefined');
-    };
-
-
     var toolbar;
     var cursor;
 
@@ -1553,8 +1525,10 @@ define([
 
                         if (APP.isDownload) {
                             var bin = getContent();
+                            if (!supportsXLSX()) {
+                                return void sframeChan.event('EV_OOIFRAME_DONE', bin, {raw: true});
+                            }
                             x2tConvertData(bin, 'filename.bin', file.type, function (xlsData) {
-                                var sframeChan = common.getSframeChannel();
                                 sframeChan.event('EV_OOIFRAME_DONE', xlsData, {raw: true});
                             });
                             return;
diff --git a/www/common/onlyoffice/ooiframe.js b/www/common/onlyoffice/ooiframe.js
index 87d5adfed..097d21e5e 100644
--- a/www/common/onlyoffice/ooiframe.js
+++ b/www/common/onlyoffice/ooiframe.js
@@ -116,6 +116,7 @@ define([
                             pathname: window.location.pathname,
                             feedbackAllowed: Utils.Feedback.state,
                             secureIframe: true,
+                            supportsWasm: Utils.Util.supportsWasm()
                         };
                         for (var k in additionalPriv) { metaObj.priv[k] = additionalPriv[k]; }
 
diff --git a/www/sheet/export.js b/www/sheet/export.js
index 58ef4a712..3d23be19c 100644
--- a/www/sheet/export.js
+++ b/www/sheet/export.js
@@ -11,8 +11,10 @@ define([], function () {
             padData: padData
         }, function (err, u8) {
             if (!u8) { return void cb(''); }
+            var ext;
+            if (typeof(u8) === "string") { ext = '.bin'; } // x2t not supported
             var blob = new Blob([u8], {type: "application/bin;charset=utf-8"});
-            cb(blob);
+            cb(blob, ext);
         }, {
             timeout: 600000,
             raw: true