diff --git a/Sources/tart/Commands/Prune.swift b/Sources/tart/Commands/Prune.swift
index cab8eaf0..a88f14a9 100644
--- a/Sources/tart/Commands/Prune.swift
+++ b/Sources/tart/Commands/Prune.swift
@@ -20,8 +20,8 @@ struct Prune: AsyncParsableCommand {
   var gc: Bool = false
 
   func validate() throws {
-    if olderThan == nil && cacheBudget == nil {
-      throw ValidationError("at least one criteria must be specified")
+    if olderThan == nil && cacheBudget == nil && !gc {
+      throw ValidationError("at least one pruning criteria must be specified")
     }
   }
 
diff --git a/Sources/tart/VM.swift b/Sources/tart/VM.swift
index da8324b9..419f24c5 100644
--- a/Sources/tart/VM.swift
+++ b/Sources/tart/VM.swift
@@ -10,7 +10,8 @@ struct NoMainScreenFoundError: Error {
 struct DownloadFailed: Error {
 }
 
-struct UnsupportedOSError: Error {
+struct UnsupportedOSError: Error, CustomStringConvertible {
+  private(set) var description: String = "error: Linux VMs are only supported on macOS 13.0 (Ventura) or newer"
 }
 
 struct UnsupportedArchitectureError: Error {