diff --git a/libphonenumber_plugin/ios/Classes/SwiftLibphonenumberPlugin.swift b/libphonenumber_plugin/ios/Classes/SwiftLibphonenumberPlugin.swift
index 266e951..d4d20e2 100644
--- a/libphonenumber_plugin/ios/Classes/SwiftLibphonenumberPlugin.swift
+++ b/libphonenumber_plugin/ios/Classes/SwiftLibphonenumberPlugin.swift
@@ -3,8 +3,8 @@ import UIKit
 import PhoneNumberKit
 
 public class SwiftLibphonenumberPlugin: NSObject, FlutterPlugin {
-    
-    let phoneNumberKit: PhoneNumberKit = PhoneNumberKit()
+
+    let phoneNumberKit: PhoneNumberUtility = PhoneNumberUtility()
     
     public static func register(with registrar: FlutterPluginRegistrar) {
         let channel = FlutterMethodChannel(name: "plugin.libphonenumber", binaryMessenger: registrar.messenger())
@@ -125,7 +125,7 @@ public class SwiftLibphonenumberPlugin: NSObject, FlutterPlugin {
         let phoneNumber = arguments["phoneNumber"] as! String
         let isoCode = arguments["isoCode"] as! String
         
-        let partialFormatter: PartialFormatter = PartialFormatter(phoneNumberKit: phoneNumberKit, defaultRegion: isoCode.uppercased())
+        let partialFormatter: PartialFormatter = PartialFormatter(utility: phoneNumberKit, defaultRegion: isoCode.uppercased())
         
         let formattedNumber = partialFormatter.formatPartial(phoneNumber)
         
diff --git a/libphonenumber_plugin/ios/libphonenumber_plugin.podspec b/libphonenumber_plugin/ios/libphonenumber_plugin.podspec
index f668b86..ae32748 100644
--- a/libphonenumber_plugin/ios/libphonenumber_plugin.podspec
+++ b/libphonenumber_plugin/ios/libphonenumber_plugin.podspec
@@ -15,7 +15,7 @@ A new flutter plugin project.
   s.source           = { :path => '.' }
   s.source_files = 'Classes/**/*'
   s.dependency 'Flutter'
-  s.dependency 'PhoneNumberKit'
+  s.dependency 'PhoneNumberKit', '~> 4.0'
   
   s.platform = :ios, '12.0'