diff --git a/spec/integ/matrix-client-methods.spec.ts b/spec/integ/matrix-client-methods.spec.ts
index 954df27fd1b..273491e70fe 100644
--- a/spec/integ/matrix-client-methods.spec.ts
+++ b/spec/integ/matrix-client-methods.spec.ts
@@ -1254,6 +1254,20 @@ describe("MatrixClient", function() {
         });
     });
 
+    describe("agreeToTerms", () => {
+        it("should send `user_accepts` via body of POST request", async () => {
+            const terms = ["https://vector.im/notice-1"];
+
+            httpBackend!.when("POST", "/terms").check(req => {
+                expect(req.data.user_accepts).toStrictEqual(terms);
+            }).respond(200, {});
+
+            const prom = client!.agreeToTerms(SERVICE_TYPES.IS, "https://vector.im", "at", terms);
+            await httpBackend!.flushAllExpected();
+            await prom;
+        });
+    });
+
     describe("publicRooms", () => {
         it("should use GET request if no server or filter is specified", () => {
             httpBackend!.when("GET", "/publicRooms").respond(200, {});
@@ -1263,7 +1277,7 @@ describe("MatrixClient", function() {
 
         it("should use GET request if only server is specified", () => {
             httpBackend!.when("GET", "/publicRooms").check(request => {
-                expect(request.queryParams.server).toBe("server1");
+                expect(request.queryParams?.server).toBe("server1");
             }).respond(200, {});
             client!.publicRooms({ server: "server1" });
             return httpBackend!.flushAllExpected();
@@ -1296,6 +1310,30 @@ describe("MatrixClient", function() {
             expect(client.http.opts.accessToken).toBe(token);
         });
     });
+
+    describe("registerWithIdentityServer", () => {
+        it("should pass data to POST request", async () => {
+            const token = {
+                access_token: "access_token",
+                token_type: "Bearer",
+                matrix_server_name: "server_name",
+                expires_in: 12345,
+            };
+
+            httpBackend!.when("POST", "/account/register").check(req => {
+                expect(req.data).toStrictEqual(token);
+            }).respond(200, {
+                access_token: "at",
+                token: "tt",
+            });
+
+            const prom = client!.registerWithIdentityServer(token);
+            await httpBackend!.flushAllExpected();
+            const resp = await prom;
+            expect(resp.access_token).toBe("at");
+            expect(resp.token).toBe("tt");
+        });
+    });
 });
 
 function withThreadId(event: MatrixEvent, newThreadId: string): MatrixEvent {
diff --git a/src/client.ts b/src/client.ts
index fc049a42089..e501f7d20db 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -8278,13 +8278,16 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * Server access token.
      * @return {module:http-api.MatrixError} Rejects: with an error response.
      */
-    public registerWithIdentityServer(hsOpenIdToken: any): Promise<any> { // TODO: Types
+    public registerWithIdentityServer(hsOpenIdToken: IOpenIDToken): Promise<{
+        access_token: string;
+        token: string;
+    }> {
         if (!this.idBaseUrl) {
             throw new Error("No identity server base URL set");
         }
 
         const uri = this.http.getUrl("/account/register", undefined, IdentityPrefix.V2, this.idBaseUrl);
-        return this.http.requestOtherUrl(Method.Post, uri, null, hsOpenIdToken);
+        return this.http.requestOtherUrl(Method.Post, uri, hsOpenIdToken);
     }
 
     /**
@@ -8751,15 +8754,14 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         baseUrl: string,
         accessToken: string,
         termsUrls: string[],
-    ): Promise<any> { // TODO: Types
+    ): Promise<{}> {
         const url = this.termsUrlForService(serviceType, baseUrl);
-        utils.encodeParams({
-            user_accepts: termsUrls,
-        }, url.searchParams);
         const headers = {
             Authorization: "Bearer " + accessToken,
         };
-        return this.http.requestOtherUrl(Method.Post, url, null, { headers });
+        return this.http.requestOtherUrl(Method.Post, url, {
+            user_accepts: termsUrls,
+        }, { headers });
     }
 
     /**