diff --git a/Package.resolved b/Package.resolved
index 34cfee5..a4a61a8 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -37,6 +37,15 @@
           "version": "9.1.0"
         }
       },
+      {
+        "package": "PromiseKit",
+        "repositoryURL": "https://github.com/mxcl/PromiseKit.git",
+        "state": {
+          "branch": null,
+          "revision": "aea48ea1855f5d82e2dffa6027afce3aab8f3dd7",
+          "version": "6.13.3"
+        }
+      },
       {
         "package": "Quick",
         "repositoryURL": "https://github.com/Quick/Quick.git",
diff --git a/Package.swift b/Package.swift
index a588682..62caf46 100644
--- a/Package.swift
+++ b/Package.swift
@@ -24,6 +24,7 @@ let package = Package(
         .package(url: "https://github.com/Carthage/Commandant.git", from: "0.18.0"),
         .package(url: "https://github.com/Quick/Nimble.git", from: "9.1.0"),
         .package(url: "https://github.com/Quick/Quick.git", from: "4.0.0"),
+        .package(url: "https://github.com/mxcl/PromiseKit.git", from: "6.13.3"),
         .package(url: "https://github.com/mxcl/Version.git", from: "2.0.0"),
     ],
     targets: [
@@ -41,7 +42,7 @@ let package = Package(
         ),
         .target(
             name: "MasKit",
-            dependencies: ["Commandant", "Version"],
+            dependencies: ["Commandant", "PromiseKit", "Version"],
             swiftSettings: [
                 .unsafeFlags([
                     "-I", "Sources/PrivateFrameworks/CommerceKit",