diff --git a/package.json b/package.json
index 2291040fa65e6be01c2539ca7cf4a3ab4a72910b..695ef1fc5b1083a57797380bd4e7fb72df9cd3ab 100644
--- a/package.json
+++ b/package.json
@@ -56,14 +56,15 @@
   },
   "devDependencies": {
     "@istanbuljs/nyc-config-typescript": "^1.0.1",
+    "@types/better-sqlite3": "^5.4.1",
     "@types/chai": "^4.2.11",
     "@types/command-line-args": "^5.0.0",
+    "@types/express": "^4.17.9",
     "@types/js-yaml": "^3.12.4",
     "@types/marked": "^1.1.0",
     "@types/mime": "^2.0.2",
     "@types/mocha": "^7.0.2",
     "@types/node": "^12",
-    "@types/better-sqlite3": "^5.4.1",
     "chai": "^4.2.0",
     "mocha": "^8.0.1",
     "nyc": "^15.1.0",
diff --git a/src/discordas.ts b/src/discordas.ts
index e69562800f68d69dd1b5795f7d08a86100e44b90..59761f00ff7e457dd165543878fbbca58133e19b 100644
--- a/src/discordas.ts
+++ b/src/discordas.ts
@@ -26,6 +26,7 @@ import * as usage from "command-line-usage";
 import * as uuid from "uuid/v4";
 import { IMatrixEvent } from "./matrixtypes";
 import { MetricPeg, PrometheusBridgeMetrics } from "./metrics";
+import { Response } from "express";
 
 const log = new Log("DiscordAS");
 
@@ -176,8 +177,12 @@ async function run() {
     const roomhandler = discordbot.RoomHandler;
     const eventProcessor = discordbot.MxEventProcessor;
 
-    // tslint:disable-next-line:no-any
-    appservice.expressAppInstance.get("/health", (_, res: any) => {
+    // 2020-12-07: If this fails to build in TypeScript with
+    // "Namespace 'serveStatic' has no exported member 'RequestHandlerConstructor'.",
+    // remove @types/express-serve-static-core and @types/serve-static from yarn.lock
+    // and run yarn.
+    // See https://github.com/DefinitelyTyped/DefinitelyTyped/issues/49595
+    appservice.expressAppInstance.get("/health", (_, res: Response) => {
         res.status(201).send("");
     });
 
diff --git a/yarn.lock b/yarn.lock
index 2bb55ea9e8095a887dd2af85dcd22f2d16ff7867..3a4d32d846b51b367dbae285267fbfa0478b29b8 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -278,9 +278,9 @@
     "@types/node" "*"
 
 "@types/express-serve-static-core@*":
-  version "4.17.13"
-  resolved "https://registry.yarnpkg.com/@types/express-serve-static-core/-/express-serve-static-core-4.17.13.tgz#d9af025e925fc8b089be37423b8d1eac781be084"
-  integrity sha512-RgDi5a4nuzam073lRGKTUIaL3eF2+H7LJvJ8eUnCI0wA6SNjXc44DCmWNiTLs/AZ7QlsFWZiw/gTG3nSQGL0fA==
+  version "4.17.14"
+  resolved "https://registry.yarnpkg.com/@types/express-serve-static-core/-/express-serve-static-core-4.17.14.tgz#cabf91debeeb3cb04b798e2cff908864e89b6106"
+  integrity sha512-uFTLwu94TfUFMToXNgRZikwPuZdOtDgs3syBtAIr/OXorL1kJqUJT9qCLnRZ5KBOWfZQikQ2xKgR2tnDj1OgDA==
   dependencies:
     "@types/node" "*"
     "@types/qs" "*"
@@ -296,6 +296,16 @@
     "@types/qs" "*"
     "@types/serve-static" "*"
 
+"@types/express@^4.17.9":
+  version "4.17.9"
+  resolved "https://registry.yarnpkg.com/@types/express/-/express-4.17.9.tgz#f5f2df6add703ff28428add52bdec8a1091b0a78"
+  integrity sha512-SDzEIZInC4sivGIFY4Sz1GG6J9UObPwCInYJjko2jzOf/Imx/dlpume6Xxwj1ORL82tBbmN4cPDIDkLbWHk9hw==
+  dependencies:
+    "@types/body-parser" "*"
+    "@types/express-serve-static-core" "*"
+    "@types/qs" "*"
+    "@types/serve-static" "*"
+
 "@types/http-cache-semantics@*":
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/@types/http-cache-semantics/-/http-cache-semantics-4.0.0.tgz#9140779736aa2655635ee756e2467d787cfe8a2a"
@@ -374,9 +384,9 @@
     "@types/node" "*"
 
 "@types/serve-static@*":
-  version "1.13.6"
-  resolved "https://registry.yarnpkg.com/@types/serve-static/-/serve-static-1.13.6.tgz#866b1b8dec41c36e28c7be40ac725b88be43c5c1"
-  integrity sha512-nuRJmv7jW7VmCVTn+IgYDkkbbDGyIINOeu/G0d74X3lm6E5KfMeQPJhxIt1ayQeQB3cSxvYs1RA/wipYoFB4EA==
+  version "1.13.8"
+  resolved "https://registry.yarnpkg.com/@types/serve-static/-/serve-static-1.13.8.tgz#851129d434433c7082148574ffec263d58309c46"
+  integrity sha512-MoJhSQreaVoL+/hurAZzIm8wafFR6ajiTM1m4A0kv6AGeVBl4r4pOV8bGFrjjq1sGxDTnCoF8i22o0/aE5XCyA==
   dependencies:
     "@types/mime" "*"
     "@types/node" "*"