diff --git a/changelog.d/205.misc b/changelog.d/205.misc
new file mode 100644
index 00000000..7af8a6f2
--- /dev/null
+++ b/changelog.d/205.misc
@@ -0,0 +1 @@
+Typescriptify ConfigValidator
\ No newline at end of file
diff --git a/package-lock.json b/package-lock.json
index 91a8eb54..f9f8c0a1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -399,6 +399,12 @@
         "@types/range-parser": "*"
       }
     },
+    "@types/extend": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/@types/extend/-/extend-3.0.1.tgz",
+      "integrity": "sha512-R1g/VyKFFI2HLC1QGAeTtCBWCo6n75l41OnsVYNbmKG+kempOESaodf6BeJyUM3Q0rKa/NQcTHbB2+66lNnxLw==",
+      "dev": true
+    },
     "@types/js-yaml": {
       "version": "3.12.5",
       "resolved": "https://registry.npmjs.org/@types/js-yaml/-/js-yaml-3.12.5.tgz",
diff --git a/package.json b/package.json
index 94a254b0..d99c8739 100644
--- a/package.json
+++ b/package.json
@@ -42,6 +42,7 @@
   },
   "devDependencies": {
     "@types/bluebird": "^3.5.32",
+    "@types/extend": "^3.0.1",
     "@types/js-yaml": "^3.12.5",
     "@types/node": "^10",
     "@types/nopt": "^3.0.29",
diff --git a/src/components/cli.ts b/src/components/cli.ts
index c3d9c3c4..dac52cae 100644
--- a/src/components/cli.ts
+++ b/src/components/cli.ts
@@ -32,7 +32,7 @@ interface CliOpts<ConfigType extends Record<string, unknown>> {
     bridgeConfig?: {
         affectsRegistration?: boolean;
         schema: string|Record<string, unknown>;
-        defaults: string|Record<string, unknown>;
+        defaults: Record<string, unknown>;
     };
     registrationPath: string;
     enableRegistration?: boolean;
diff --git a/src/components/config-validator.js b/src/components/config-validator.js
deleted file mode 100644
index 6d78d861..00000000
--- a/src/components/config-validator.js
+++ /dev/null
@@ -1,69 +0,0 @@
-/*
-Copyright 2020 The Matrix.org Foundation C.I.C.
-
-Licensed under the Apache License, Version 2.0 (the "License");
-you may not use this file except in compliance with the License.
-You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-Unless required by applicable law or agreed to in writing, software
-distributed under the License is distributed on an "AS IS" BASIS,
-WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-See the License for the specific language governing permissions and
-limitations under the License.
-*/
-
-const fs = require("fs");
-const yaml = require("js-yaml");
-const Validator = require("is-my-json-valid");
-const extend = require("extend");
-
-/**
- * Construct a validator of YAML files.
- * @constructor
- * @param {string|Object} schema The JSON schema file (as YAML) or object.
- */
-function ConfigValidator(schema) {
-    this.schema = schema;
-    if (typeof schema === "string") {
-        this.schema = this._loadFromFile(schema);
-    }
-}
-
-/**
- * Validate the input config.
- * @param {string|Object} inputConfig The input config file path (string) or
- * parsed config (Object).
- * @param {Object=} defaultConfig The default config options.
- * @return {Object} The input config with defaults applied.
- * @throws On validation errors
- */
-ConfigValidator.prototype.validate = function(inputConfig, defaultConfig) {
-    defaultConfig = defaultConfig || {};
-    if (typeof inputConfig === "string") {
-        inputConfig = this._loadFromFile(inputConfig);
-    }
-    const js = Validator(this.schema, {
-        verbose: true,
-    });
-    const res = js(inputConfig, this.schema);
-    if (!res) {
-        js.errors.forEach(function(error) {
-            console.error(JSON.stringify(error));
-            console.error(`The field ${error.field} is ${error.value}` +
-                          ` which ${error.message}`);
-        });
-        var e = new Error("Failed to validate file");
-        e._validationErrors = js.errors;
-        throw e;
-    }
-    // mux in the default config
-    return extend(true, defaultConfig, inputConfig);
-}
-
-ConfigValidator.prototype._loadFromFile = function(filename) {
-    return yaml.safeLoad(fs.readFileSync(filename, 'utf8'));
-};
-
-module.exports = ConfigValidator;
diff --git a/src/components/config-validator.ts b/src/components/config-validator.ts
new file mode 100644
index 00000000..727171d4
--- /dev/null
+++ b/src/components/config-validator.ts
@@ -0,0 +1,75 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+import * as fs from "fs";
+import yaml from "js-yaml";
+import validator from "is-my-json-valid";
+import extend from "extend";
+
+type Schema = any;
+
+export default class ConfigValidator {
+
+    /**
+     * Construct a validator of YAML files.
+     * @param schema The JSON schema file object.
+     */
+    constructor (private schema: Schema) { }
+
+    /**
+     * Validate the input config.
+     * @param inputConfig The input config file path (string) or
+     * parsed config (Object).
+     * @param defaultConfig The default config options.
+     * @return The input config with defaults applied.
+     * @throws On validation errors
+     */
+    public validate(inputConfig: string|Schema, defaultConfig: Record<string, unknown> = {}) {
+        if (typeof inputConfig === "string") {
+            inputConfig = ConfigValidator.loadFromFile(inputConfig);
+        }
+        const js = validator(this.schema, {
+            verbose: true,
+        });
+        const res = js(inputConfig, this.schema);
+        if (!res) {
+            js.errors.forEach(error => {
+                console.error(JSON.stringify(error));
+                console.error(`The field ${error.field} is ${error.value}` +
+                            ` which ${error.message}`);
+            });
+            // This is a bit awful, but it's how we return validation errors.
+            const e: any = new Error("Failed to validate file");
+            e._validationErrors = js.errors;
+            throw e;
+        }
+        // mux in the default config
+        return extend(true, defaultConfig, inputConfig);
+    }
+
+    private static loadFromFile(filename: string): Schema {
+        const result = yaml.safeLoad(fs.readFileSync(filename, 'utf8'));
+        if (typeof(result) !== "object") {
+            throw Error('Was expecting yaml as an object');
+        }
+        return result;
+    }
+
+    private static fromSchemaFile(filename: string): ConfigValidator {
+        return new ConfigValidator(ConfigValidator.loadFromFile(filename));
+    }
+}
+
+module.exports = ConfigValidator;
diff --git a/src/index.ts b/src/index.ts
index 49bfe6d5..f99c7409 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -27,6 +27,7 @@ export * from "./components/state-lookup";
 
 // Config and CLI
 export * from "./components/cli";
+export * from "./components/config-validator";
 module.exports.ConfigValidator = require("./components/config-validator");
 
 // Store