diff --git a/WBCore/WBManager.swift b/WBCore/WBManager.swift
index 48ac616..c5526b6 100644
--- a/WBCore/WBManager.swift
+++ b/WBCore/WBManager.swift
@@ -181,6 +181,27 @@ open class WBManager: NSObject, CBCentralManagerDelegate, WKScriptMessageHandler
             }
             device.triage(view)
         case .requestDevice:
+            if (centralManager.state != CBManagerState.poweredOn) {
+                transaction.resolveAsFailure(withMessage: "Bluetooth not activated.")
+                stopScanForPeripherals()
+                requestDeviceTransaction = nil
+                clearState()
+                
+                let alert = UIAlertController(title: NSLocalizedString("turn_on_bluetooth_title", comment: "Turn on bluetooth."), message: NSLocalizedString("turn_on_bluetooth_body", comment: "Please turn on bluetooth."), preferredStyle: .alert)
+                alert.addAction(UIAlertAction(title: "Ok", style: .default, handler: nil))
+                
+                // Find top most ViewController.
+                let keyWindow = UIApplication.shared.windows.filter {$0.isKeyWindow}.first
+                if var topController = keyWindow?.rootViewController {
+                    while let presentedViewController = topController.presentedViewController {
+                        topController = presentedViewController
+                    }
+                    
+                    topController.present(alert, animated: true)
+                }
+                
+                return
+            }
             guard transaction.key.typeComponents.count == 1
             else {
                 transaction.resolveAsFailure(withMessage: "Invalid request type \(transaction.key)")