diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index 7e70255af3..3147d878f7 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -1,5 +1,5 @@
 module.exports = {
-    plugins: ["matrix-org", "import", "jsdoc"],
+    plugins: ["matrix-org", "import", "jsdoc", "node"],
     extends: ["plugin:matrix-org/babel", "plugin:matrix-org/jest", "plugin:import/typescript"],
     parserOptions: {
         project: ["./tsconfig.json"],
@@ -128,6 +128,14 @@ module.exports = {
                 // These need a bit more work before we can enable
                 // "jsdoc/check-param-names": "error",
                 // "jsdoc/check-indentation": "error",
+                // Ensure .ts extension on imports outside of tests
+                "node/file-extension-in-import": [
+                    "error",
+                    "always",
+                    {
+                        tryExtensions: [".ts"],
+                    },
+                ],
             },
         },
         {
diff --git a/package.json b/package.json
index 6680f069d3..b9132f43e2 100644
--- a/package.json
+++ b/package.json
@@ -100,6 +100,7 @@
         "eslint-plugin-jest": "^28.0.0",
         "eslint-plugin-jsdoc": "^50.0.0",
         "eslint-plugin-matrix-org": "^1.0.0",
+        "eslint-plugin-node": "^11.1.0",
         "eslint-plugin-tsdoc": "^0.3.0",
         "eslint-plugin-unicorn": "^55.0.0",
         "fake-indexeddb": "^5.0.2",
diff --git a/src/client.ts b/src/client.ts
index 9273281a07..3a9860b3a8 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -2254,6 +2254,8 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         // importing rust-crypto will download the webassembly, so we delay it until we know it will be
         // needed.
         this.logger.debug("Downloading Rust crypto library");
+        // blocked on https://github.com/matrix-org/matrix-js-sdk/issues/4392 / https://github.com/babel/babel/issues/16750
+        // eslint-disable-next-line node/file-extension-in-import
         const RustCrypto = await import("./rust-crypto");
 
         const rustCrypto = await RustCrypto.initRustCrypto({
diff --git a/yarn.lock b/yarn.lock
index 643111f73a..83f6c7b31e 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3014,6 +3014,14 @@ eslint-module-utils@^2.8.1:
   dependencies:
     debug "^3.2.7"
 
+eslint-plugin-es@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-es/-/eslint-plugin-es-3.0.1.tgz#75a7cdfdccddc0589934aeeb384175f221c57893"
+  integrity sha512-GUmAsJaN4Fc7Gbtl8uOBlayo2DqhwWvEzykMHSCZHU3XdJ+NSzzZcVhXh3VxX5icqQ+oQdIEawXX8xkR3mIFmQ==
+  dependencies:
+    eslint-utils "^2.0.0"
+    regexpp "^3.0.0"
+
 eslint-plugin-import@^2.26.0:
   version "2.29.1"
   resolved "https://registry.yarnpkg.com/eslint-plugin-import/-/eslint-plugin-import-2.29.1.tgz#d45b37b5ef5901d639c15270d74d46d161150643"
@@ -3066,6 +3074,18 @@ eslint-plugin-matrix-org@^1.0.0:
   resolved "https://registry.yarnpkg.com/eslint-plugin-matrix-org/-/eslint-plugin-matrix-org-1.2.1.tgz#76d1505daa93fb99ba4156008b9b32f57682c9b1"
   integrity sha512-A3cDjhG7RHwfCS8o3bOip8hSCsxtmgk2ahvqE5v/Ic2kPEZxixY6w8zLj7hFGsrRmPSEpLWqkVLt8uvQBapiQA==
 
+eslint-plugin-node@^11.1.0:
+  version "11.1.0"
+  resolved "https://registry.yarnpkg.com/eslint-plugin-node/-/eslint-plugin-node-11.1.0.tgz#c95544416ee4ada26740a30474eefc5402dc671d"
+  integrity sha512-oUwtPJ1W0SKD0Tr+wqu92c5xuCeQqB3hSCHasn/ZgjFdA9iDGNkNf2Zi9ztY7X+hNuMib23LNGRm6+uN+KLE3g==
+  dependencies:
+    eslint-plugin-es "^3.0.0"
+    eslint-utils "^2.0.0"
+    ignore "^5.1.1"
+    minimatch "^3.0.4"
+    resolve "^1.10.1"
+    semver "^6.1.0"
+
 eslint-plugin-tsdoc@^0.3.0:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/eslint-plugin-tsdoc/-/eslint-plugin-tsdoc-0.3.0.tgz#e4498070355cac2b9f38ea497ba83016bb7eda62"
@@ -3117,6 +3137,18 @@ eslint-scope@^7.2.2:
     esrecurse "^4.3.0"
     estraverse "^5.2.0"
 
+eslint-utils@^2.0.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-2.1.0.tgz#d2de5e03424e707dc10c74068ddedae708741b27"
+  integrity sha512-w94dQYoauyvlDc43XnGB8lU3Zt713vNChgt4EWwhXAP2XkBvndfxF0AgIqKOOasjPIPzj9JqgwkwbCYD0/V3Zg==
+  dependencies:
+    eslint-visitor-keys "^1.1.0"
+
+eslint-visitor-keys@^1.1.0:
+  version "1.3.0"
+  resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.3.0.tgz#30ebd1ef7c2fdff01c3a4f151044af25fab0523e"
+  integrity sha512-6J72N8UNa462wa/KFODt/PJ3IU60SDpC3QXC1Hjc1BXXpfL2C9R5+AU7jhe0F6GREqVMh4Juu+NY7xn+6dipUQ==
+
 eslint-visitor-keys@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-2.1.0.tgz#f65328259305927392c938ed44eb0a5c9b2bd303"
@@ -3733,7 +3765,7 @@ iconv-lite@0.6.3:
   dependencies:
     safer-buffer ">= 2.1.2 < 3.0.0"
 
-ignore@^5.1.8, ignore@^5.2.0, ignore@^5.3.1:
+ignore@^5.1.1, ignore@^5.1.8, ignore@^5.2.0, ignore@^5.3.1:
   version "5.3.2"
   resolved "https://registry.yarnpkg.com/ignore/-/ignore-5.3.2.tgz#3cd40e729f3643fd87cb04e50bf0eb722bc596f5"
   integrity sha512-hsBTNUqQTDwkWtcdYI2i06Y/nUBEsNEDJKjWdigLvegy8kDuJAS8uRlpkkcQpyEXL0Z/pjDy5HBmMjRCJ2gq+g==
@@ -5436,6 +5468,11 @@ regexparam@^3.0.0:
   resolved "https://registry.yarnpkg.com/regexparam/-/regexparam-3.0.0.tgz#1673e09d41cb7fd41eaafd4040a6aa90daa0a21a"
   integrity sha512-RSYAtP31mvYLkAHrOlh25pCNQ5hWnT106VukGaaFfuJrZFkGRX5GhUAdPqpSDXxOhA2c4akmRuplv1mRqnBn6Q==
 
+regexpp@^3.0.0:
+  version "3.2.0"
+  resolved "https://registry.yarnpkg.com/regexpp/-/regexpp-3.2.0.tgz#0425a2768d8f23bad70ca4b90461fa2f1213e1b2"
+  integrity sha512-pq2bWo9mVD43nbts2wGv17XLiNLya+GklZ8kaDLV2Z08gDCsGpnKn9BFMepvWuHCbyVvY7J5o5+BVvoQbmlJLg==
+
 regexpu-core@^5.3.1:
   version "5.3.2"
   resolved "https://registry.yarnpkg.com/regexpu-core/-/regexpu-core-5.3.2.tgz#11a2b06884f3527aec3e93dbbf4a3b958a95546b"
@@ -5504,7 +5541,7 @@ resolve.exports@^2.0.0:
   resolved "https://registry.yarnpkg.com/resolve.exports/-/resolve.exports-2.0.2.tgz#f8c934b8e6a13f539e38b7098e2e36134f01e800"
   integrity sha512-X2UW6Nw3n/aMgDVy+0rSqgHlv39WZAlZrXCdnbyEiKm17DSqHX4MmQMaST3FbeWR5FTuRcUwYAziZajji0Y7mg==
 
-resolve@^1.10.0, resolve@^1.14.2, resolve@^1.20.0, resolve@^1.22.4, resolve@~1.22.2:
+resolve@^1.10.0, resolve@^1.10.1, resolve@^1.14.2, resolve@^1.20.0, resolve@^1.22.4, resolve@~1.22.2:
   version "1.22.8"
   resolved "https://registry.yarnpkg.com/resolve/-/resolve-1.22.8.tgz#b6c87a9f2aa06dfab52e3d70ac8cde321fa5a48d"
   integrity sha512-oKWePCxqpd6FlLvGV1VU0x7bkPmmCNolxzjMf4NczoDnQcIWrAF+cPtZn5i6n+RfD2d9i0tzpKnG6Yk168yIyw==
@@ -5604,7 +5641,7 @@ sdp-transform@^2.14.1:
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.7.2.tgz#48d55db737c3287cd4835e17fa13feace1c41ef8"
   integrity sha512-cBznnQ9KjJqU67B52RMC65CMarK2600WFnbkcaiwWq3xy/5haFJlshgnpjovMVJ+Hff49d8GEn0b87C5pDQ10g==
 
-semver@^6.3.0, semver@^6.3.1:
+semver@^6.1.0, semver@^6.3.0, semver@^6.3.1:
   version "6.3.1"
   resolved "https://registry.yarnpkg.com/semver/-/semver-6.3.1.tgz#556d2ef8689146e46dcea4bfdd095f3434dffcb4"
   integrity sha512-BR7VvDCVHO+q2xBEWskxS6DJE1qRnb7DxzUrogb71CWoSficBxYsiAGd+Kl0mmq/MprG9yArRkyrQxTO6XjMzA==