diff --git a/Sources/Scaledrone/Classes/Scaledrone.swift b/Sources/Scaledrone/Classes/Scaledrone.swift
index c05ecf5..9f72af4 100644
--- a/Sources/Scaledrone/Classes/Scaledrone.swift
+++ b/Sources/Scaledrone/Classes/Scaledrone.swift
@@ -85,8 +85,12 @@ public class Scaledrone: WebSocketDelegate {
             "type": "handshake",
             "channel": self.channelID,
             "callback": createCallback(fn: { data in
-                self.clientID = data["client_id"] as! String
-                self.delegate?.scaledroneDidConnect(scaledrone: self, error: data["error"] as? NSError)
+                if let clientID = data["client_id"] as? String {
+                    self.clientID = clientID
+                    self.delegate?.scaledroneDidConnect(scaledrone: self, error: data["error"] as? NSError)
+                } else {
+                    self.delegate?.scaledroneDidReceiveError(scaledrone: self, error: data["error"] as? NSError)
+                }
             })
             ] as [String : Any]
         if (self.data != nil) {