diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e2b1110..4b93c25 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,3 +11,7 @@ TODO
 - To fix code quality: `script/lint/fix`
 - To check formatting: `script/format/check`
 - To fix formatting: `script/format/fix`
+
+## How to build
+
+TODO
diff --git a/Package.swift b/Package.swift
index c716370..ce0e777 100644
--- a/Package.swift
+++ b/Package.swift
@@ -5,6 +5,12 @@ import PackageDescription
 
 let package = Package(
     name: "AblyChat",
+    // These platforms are copied from ably-cocoa; I imagine we’ll make them more restrictive as we start to make use of more Swift features in the project. 
+    platforms: [
+        .macOS(.v10_11),
+        .iOS(.v9),
+        .tvOS(.v10)
+    ],
     products: [
         // Products define the executables and libraries a package produces, making them visible to other packages.
         .library(