diff --git a/ts/package.json b/ts/package.json
index 55fe04261..c78d73277 100644
--- a/ts/package.json
+++ b/ts/package.json
@@ -45,7 +45,7 @@
         "svelte": "^3.25.0",
         "svelte-check": "^1.0.61",
         "svelte-preprocess": "^4.6.9",
-        "svelte2tsx": "^0.1.133",
+        "svelte2tsx": "^0.4.6",
         "tmp": "^0.2.1",
         "tslib": "^2.0.3",
         "typescript": "^4.4.0",
diff --git a/ts/svelte/svelte.ts b/ts/svelte/svelte.ts
index 324461aa0..958544446 100644
--- a/ts/svelte/svelte.ts
+++ b/ts/svelte/svelte.ts
@@ -2,10 +2,10 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 // languageServerHost taken from MIT sources - see below.
 
-const fs = require("fs");
-const worker = require("@bazel/worker");
-const svelte2tsx = require("svelte2tsx");
-const preprocess = require("svelte-preprocess");
+import * as fs from "fs";
+import * as worker from "@bazel/worker";
+import { svelte2tsx } from "svelte2tsx";
+import preprocess from "svelte-preprocess";
 import { basename } from "path";
 import * as ts from "typescript";
 import * as svelte from "svelte/compiler.js";
@@ -132,13 +132,10 @@ async function writeDts(tsPath, dtsPath, tsLibs) {
 function writeTs(svelteSource, sveltePath, tsPath): void {
     let tsSource = svelte2tsx(svelteSource, {
         filename: sveltePath,
-        strictMode: true,
         isTsFile: true,
+        mode: "dts",
     });
     let codeLines = tsSource.code.split("\n");
-    // replace the "///<reference types="svelte" />" with a line
-    // turning off checking, as we'll use svelte-check for that
-    codeLines[0] = "// @ts-nocheck";
     updateFileContent(tsPath, codeLines.join("\n"));
 }
 
@@ -164,10 +161,11 @@ async function writeJs(
             ],
         },
     });
-    preprocessOptions.filename = inputFilename;
 
     try {
-        const processed = await svelte.preprocess(source, preprocessOptions);
+        const processed = await svelte.preprocess(source, preprocessOptions, {
+            filename: inputFilename,
+        });
         const result = svelte.compile(processed.toString!(), {
             format: "esm",
             css: false,
diff --git a/ts/yarn.lock b/ts/yarn.lock
index c0e984a50..bf382404e 100644
--- a/ts/yarn.lock
+++ b/ts/yarn.lock
@@ -4306,10 +4306,10 @@ svelte-preprocess@^4.0.0, svelte-preprocess@^4.6.9:
     sorcery "^0.10.0"
     strip-indent "^3.0.0"
 
-svelte2tsx@^0.1.133:
-  version "0.1.193"
-  resolved "https://registry.yarnpkg.com/svelte2tsx/-/svelte2tsx-0.1.193.tgz#16fe594898ef455e4f715ac317d219c9c757656b"
-  integrity sha512-vzy4YQNYDnoqp2iZPnJy7kpPAY6y121L0HKrSBjU/IWW7DQ6T7RMJed2VVHFmVYm0zAGYMDl9urPc6R4DDUyhg==
+svelte2tsx@^0.4.6:
+  version "0.4.6"
+  resolved "https://registry.yarnpkg.com/svelte2tsx/-/svelte2tsx-0.4.6.tgz#3435064962c910c0a075b4a1c04e91eaf568f5e5"
+  integrity sha512-flljgh/MbJDijo6Z1HhCfyzdRgn1Nd7QTuuxk9Oq5CzyBXZl/NJYh4otZZwUHnx5poy8k7Oxr2CBE3IBh89tmQ==
   dependencies:
     dedent-js "^1.0.1"
     pascal-case "^3.1.1"