diff --git a/ShadowsocksX-NG/ProxyInterfacesViewCtrl.swift b/ShadowsocksX-NG/ProxyInterfacesViewCtrl.swift
index 10cd210..12ee19b 100644
--- a/ShadowsocksX-NG/ProxyInterfacesViewCtrl.swift
+++ b/ShadowsocksX-NG/ProxyInterfacesViewCtrl.swift
@@ -28,7 +28,7 @@ class ProxyInterfacesViewCtrl: NSViewController, NSTableViewDataSource, NSTableV
             selectedNetworkServices = NSMutableSet()
         }
         
-        networkServices = ProxyConfTool.networkServicesList() as NSArray!
+        networkServices = ProxyConfTool.networkServicesList() as NSArray?
         tableView.reloadData()
     }
 
diff --git a/ShadowsocksX-NG/ServerProfile.swift b/ShadowsocksX-NG/ServerProfile.swift
index efc6173..807a002 100644
--- a/ShadowsocksX-NG/ServerProfile.swift
+++ b/ShadowsocksX-NG/ServerProfile.swift
@@ -39,7 +39,7 @@ class ServerProfile: NSObject, NSCopying {
         self.init()
 
         func padBase64(string: String) -> String {
-            var length = string.characters.count
+            var length = string.utf8.count
             if length % 4 == 0 {
                 return string
             } else {
@@ -90,7 +90,7 @@ class ServerProfile: NSObject, NSCopying {
                 return nil
             }
 
-            let parts = userInfo.characters.split(separator: ":", maxSplits: 1, omittingEmptySubsequences: false)
+            let parts = userInfo.split(separator: ":", maxSplits: 1, omittingEmptySubsequences: false)
             if parts.count != 2 {
                 return nil
             }