             return
         }
         XCTAssertEqual(0, packetBytes.readableBytes) // check nothing is left over
-        guard let tcpIPPacket = payload.payload.readTCPIPv4() else {
+        guard let tcpIPPacket = try payload.payload.readTCPIPv4() else {
             XCTFail("couldn't read TCP/IPv4 packet")
             return
         }

        XCTAssertEqual(expectedData, actualData)
    }
    
    func testOversizedOutboundDataComesAsTwoPacketsIPv6() {
        self.channel.localAddress = try! SocketAddress(ipAddress: "::1", port: 1111)
        self.channel.remoteAddress = try! SocketAddress(ipAddress: "::2", port: 2222)
        let expectedData = String(repeating: "X", count: Int(UInt16.max) * 2 - 300)

            return
        }
        XCTAssertEqual(0, packetBytes.readableBytes) // check nothing is left over
        guard let tcpIPPacket1 = try payload1.payload.readTCPIPv6(),
            let tcpIPPacket2 = try payload2.payload.readTCPIPv6() else {
            XCTFail("couldn't read TCP/IPv6 packets")
            return
        }
