diff --git a/package-lock.json b/package-lock.json
index ddf7f538..02517050 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -2915,9 +2915,9 @@
       "integrity": "sha512-9UjMCHK5GPgQRoNbqdLIAvAy0EInuiqbW0PBMtVP6B5B2HQJlvoJHM+KodPZMEjOa5VkSc+5LH7xy+cUzQdmHw=="
     },
     "@types/ws": {
-      "version": "7.4.1",
-      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-7.4.1.tgz",
-      "integrity": "sha512-ISCK1iFnR+jYv7+jLNX0wDqesZ/5RAeY3wUx6QaphmocphU61h+b+PHjS18TF4WIPTu/MMzxIq2PHr32o2TS5Q==",
+      "version": "7.4.7",
+      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-7.4.7.tgz",
+      "integrity": "sha512-JQbbmxZTZehdc2iszGKs5oC3NFnjeay7mtAWrdt7qNtAVK0g19muApzAy4bm9byz79xa2ZnO/BOBC2R8RC5Lww==",
       "dev": true,
       "requires": {
         "@types/node": "*"
diff --git a/package.json b/package.json
index cb7a7a94..16679928 100644
--- a/package.json
+++ b/package.json
@@ -54,7 +54,7 @@
     "@relaycorp/ws-mock": "^2.4.1",
     "@types/jest": "^26.0.24",
     "@types/verror": "^1.10.5",
-    "@types/ws": "^7.4.1",
+    "@types/ws": "^7.4.7",
     "axios-mock-adapter": "^1.19.0",
     "del-cli": "^4.0.1",
     "jest": "^27.0.6",
diff --git a/src/lib/PoWebClient.ts b/src/lib/PoWebClient.ts
index e06424fe..ec528b42 100644
--- a/src/lib/PoWebClient.ts
+++ b/src/lib/PoWebClient.ts
@@ -296,7 +296,7 @@ export class PoWebClient implements GSCClient {
       ws.once('message', async (message) => {
         let challenge: HandshakeChallenge;
         try {
-          challenge = HandshakeChallenge.deserialize(bufferToArray(message));
+          challenge = HandshakeChallenge.deserialize(bufferToArray(message as Buffer));
         } catch (error) {
           ws.close(WebSocketCode.CANNOT_ACCEPT, 'Malformed handshake challenge');
           reject(