diff --git a/Sources/mas/main.swift b/Sources/mas/main.swift
index e87296080..cb6912dfa 100644
--- a/Sources/mas/main.swift
+++ b/Sources/mas/main.swift
@@ -7,10 +7,19 @@
 //
 
 import Commandant
+import Foundation
 import MasKit
 
 MasKit.initialize()
 
+let monterey = OperatingSystemVersion(majorVersion: 12, minorVersion: 0, patchVersion: 0)
+if ProcessInfo.processInfo.isOperatingSystemAtLeast(monterey) {
+    printWarning(
+        "mas is not yet functional on macOS Monterey (12) due to changes in macOS frameworks. "
+            + "To track progress or to *contribute* to fixing this issue, please see: "
+            + "https://github.com/mas-cli/mas/issues/417")
+}
+
 let registry = CommandRegistry<MASError>()
 let helpCommand = HelpCommand(registry: registry)