diff --git a/Source/SocketIO/Client/SocketIOClientOption.swift b/Source/SocketIO/Client/SocketIOClientOption.swift
index 97a5836..ff77265 100644
--- a/Source/SocketIO/Client/SocketIOClientOption.swift
+++ b/Source/SocketIO/Client/SocketIOClientOption.swift
@@ -22,6 +22,7 @@
 //  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 //  THE SOFTWARE.
 
+import Dispatch
 import Foundation
 #if !os(Linux)
 import StarscreamSocketIO
diff --git a/Source/SocketIO/Engine/SocketEngineClient.swift b/Source/SocketIO/Engine/SocketEngineClient.swift
index dc2692c..e2a507d 100644
--- a/Source/SocketIO/Engine/SocketEngineClient.swift
+++ b/Source/SocketIO/Engine/SocketEngineClient.swift
@@ -25,6 +25,7 @@
 
 import Foundation
 
+#if !os(Linux)
 /// Declares that a type will be a delegate to an engine.
 @objc public protocol SocketEngineClient {
     // MARK: Methods
@@ -54,3 +55,34 @@ import Foundation
     /// - parameter data: The data the engine received.
     func parseEngineBinaryData(_ data: Data)
 }
+#else
+/// Declares that a type will be a delegate to an engine.
+public protocol SocketEngineClient : class {
+    // MARK: Methods
+
+    /// Called when the engine errors.
+    ///
+    /// - parameter reason: The reason the engine errored.
+    func engineDidError(reason: String)
+
+    /// Called when the engine closes.
+    ///
+    /// - parameter reason: The reason that the engine closed.
+    func engineDidClose(reason: String)
+
+    /// Called when the engine opens.
+    ///
+    /// - parameter reason: The reason the engine opened.
+    func engineDidOpen(reason: String)
+
+    /// Called when the engine has a message that must be parsed.
+    ///
+    /// - parameter msg: The message that needs parsing.
+    func parseEngineMessage(_ msg: String)
+
+    /// Called when the engine receives binary data.
+    ///
+    /// - parameter data: The data the engine received.
+    func parseEngineBinaryData(_ data: Data)
+}
+#endif
diff --git a/Source/SocketIO/Engine/SocketEngineSpec.swift b/Source/SocketIO/Engine/SocketEngineSpec.swift
index 161f7c9..5554a27 100644
--- a/Source/SocketIO/Engine/SocketEngineSpec.swift
+++ b/Source/SocketIO/Engine/SocketEngineSpec.swift
@@ -23,6 +23,7 @@
 //  THE SOFTWARE.
 //
 
+import Dispatch
 import Foundation
 #if !os(Linux)
 import StarscreamSocketIO
@@ -30,6 +31,7 @@ import StarscreamSocketIO
 import WebSockets
 #endif
 
+#if !os(Linux)
 /// Specifies a SocketEngine.
 @objc public protocol SocketEngineSpec {
     /// The client for this engine.
@@ -74,6 +76,123 @@ import WebSockets
     /// Whether or not this engine uses secure transports
     var secure: Bool { get }
 
+    /// A custom security validator for Starscream. Useful for SSL pinning.
+    var security: SSLSecurity? { get }
+
+    /// Whether or not to allow self signed certificates.
+    var selfSigned: Bool { get }
+
+    /// The session id for this engine.
+    var sid: String { get }
+
+    /// The path to engine.io.
+    var socketPath: String { get }
+
+    /// The url for polling.
+    var urlPolling: URL { get }
+
+    /// The url for WebSockets.
+    var urlWebSocket: URL { get }
+
+    /// If `true`, then the engine is currently in WebSockets mode.
+    var websocket: Bool { get }
+
+    /// The WebSocket for this engine.
+    var ws: WebSocket? { get set }
+
+    /// Creates a new engine.
+    ///
+    /// - parameter client: The client for this engine.
+    /// - parameter url: The url for this engine.
+    /// - parameter options: The options for this engine.
+    init(client: SocketEngineClient, url: URL, options: NSDictionary?)
+
+    /// Starts the connection to the server.
+    func connect()
+
+    /// Called when an error happens during execution. Causes a disconnection.
+    func didError(reason: String)
+
+    /// Disconnects from the server.
+    ///
+    /// - parameter reason: The reason for the disconnection. This is communicated up to the client.
+    func disconnect(reason: String)
+
+    /// Called to switch from HTTP long-polling to WebSockets. After calling this method the engine will be in
+    /// WebSocket mode.
+    ///
+    /// **You shouldn't call this directly**
+    func doFastUpgrade()
+
+    /// Causes any packets that were waiting for POSTing to be sent through the WebSocket. This happens because when
+    /// the engine is attempting to upgrade to WebSocket it does not do any POSTing.
+    ///
+    /// **You shouldn't call this directly**
+    func flushWaitingForPostToWebSocket()
+
+    /// Parses raw binary received from engine.io.
+    ///
+    /// - parameter data: The data to parse.
+    func parseEngineData(_ data: Data)
+
+    /// Parses a raw engine.io packet.
+    ///
+    /// - parameter message: The message to parse.
+    /// - parameter fromPolling: Whether this message is from long-polling.
+    ///                          If `true` we might have to fix utf8 encoding.
+    func parseEngineMessage(_ message: String)
+
+    /// Writes a message to engine.io, independent of transport.
+    ///
+    /// - parameter msg: The message to send.
+    /// - parameter withType: The type of this message.
+    /// - parameter withData: Any data that this message has.
+    func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data])
+}
+#else
+public protocol SocketEngineSpec : class {
+    /// The client for this engine.
+    var client: SocketEngineClient? { get set }
+
+    /// `true` if this engine is closed.
+    var closed: Bool { get }
+
+    /// `true` if this engine is connected. Connected means that the initial poll connect has succeeded.
+    var connected: Bool { get }
+
+    /// The connect parameters sent during a connect.
+    var connectParams: [String: Any]? { get set }
+
+    /// Whether or not to use WebSocket compression.
+    var compress: Bool { get }
+
+    /// An array of HTTPCookies that are sent during the connection.
+    var cookies: [HTTPCookie]? { get }
+
+    /// The queue that all engine actions take place on.
+    var engineQueue: DispatchQueue { get }
+
+    /// A dictionary of extra http headers that will be set during connection.
+    var extraHeaders: [String: String]? { get }
+
+    /// When `true`, the engine is in the process of switching to WebSockets.
+    var fastUpgrade: Bool { get }
+
+    /// When `true`, the engine will only use HTTP long-polling as a transport.
+    var forcePolling: Bool { get }
+
+    /// When `true`, the engine will only use WebSockets as a transport.
+    var forceWebsockets: Bool { get }
+
+    /// If `true`, the engine is currently in HTTP long-polling mode.
+    var polling: Bool { get }
+
+    /// If `true`, the engine is currently seeing whether it can upgrade to WebSockets.
+    var probing: Bool { get }
+
+    /// Whether or not this engine uses secure transports
+    var secure: Bool { get }
+
     var security: SSLSecurity? { get }
 
     /// Whether or not to allow self signed certificates.
@@ -146,6 +265,7 @@ import WebSockets
     /// - parameter withData: Any data that this message has.
     func write(_ msg: String, withType type: SocketEnginePacketType, withData data: [Data])
 }
+#endif
 
 extension SocketEngineSpec {
     var urlPollingWithSid: URL {