diff --git a/Package.swift b/Package.swift
index 984e8c1..2e0d331 100644
--- a/Package.swift
+++ b/Package.swift
@@ -3,7 +3,7 @@ import PackageDescription
 let package = Package(
     name: "PMKAlamofire",
     dependencies: [
-        .Package(url: "https://github.com/mxcl/PromiseKit.git", majorVersion: 4),
+        .Package(url: "https://github.com/mxcl/PromiseKit.git", majorVersion: 6),
         .Package(url: "https://github.com/Alamofire/Alamofire.git", majorVersion: 4)
     ],
     exclude: ["Tests"]