diff --git a/Package.swift b/Package.swift
index 4b1e49b..fb5f1f1 100644
--- a/Package.swift
+++ b/Package.swift
@@ -5,6 +5,9 @@ import PackageDescription
 
 let package = Package(
     name: "TerminalUI",
+    platforms: [
+        .macOS("10.15"),
+    ],
     products: [
         // Products define the executables and libraries a package produces, and make them visible to other packages.
         .library(