diff --git a/Sources/XcodesKit/Models+Runtimes.swift b/Sources/XcodesKit/Models+Runtimes.swift
index 6463569..9817133 100644
--- a/Sources/XcodesKit/Models+Runtimes.swift
+++ b/Sources/XcodesKit/Models+Runtimes.swift
@@ -11,7 +11,7 @@ struct DownloadableRuntimesResponse: Decodable {
 public struct DownloadableRuntime: Decodable {
     let category: Category
     let simulatorVersion: SimulatorVersion
-    let source: String
+    let source: String?
     let dictionaryVersion: Int
     let contentType: ContentType
     let platform: Platform
@@ -36,6 +36,17 @@ public struct DownloadableRuntime: Decodable {
     var visibleIdentifier: String {
         return platform.shortName + " " + completeVersion
     }
+
+    var sourceURL: URL {
+        source.flatMap(URL.init) ?? makeRuntimeURL(runtimeName: name)
+    }
+}
+
+let xcodeRuntimesFallbackURL = URL(string: "https://download.developer.apple.com/Developer_Tools/")!
+
+func makeRuntimeURL(runtimeName: String) -> URL {
+    let baseName = runtimeName.replacingOccurrences(of: ".0 ", with: " ").replacingOccurrences(of: " ", with: "_")
+    return xcodeRuntimesFallbackURL.appendingPathComponent("\(baseName)/\(baseName).dmg")
 }
 
 func makeVersion(for osVersion: String, betaNumber: Int?) -> String {
@@ -79,6 +90,7 @@ extension DownloadableRuntime {
     enum ContentType: String, Decodable {
         case diskImage = "diskImage"
         case package = "package"
+        case cryptexDiskImage = "cryptexDiskImage"
     }
 
     enum Platform: String, Decodable {
diff --git a/Sources/XcodesKit/RuntimeInstaller.swift b/Sources/XcodesKit/RuntimeInstaller.swift
index cf0821c..dc00420 100644
--- a/Sources/XcodesKit/RuntimeInstaller.swift
+++ b/Sources/XcodesKit/RuntimeInstaller.swift
@@ -110,7 +110,7 @@ public class RuntimeInstaller {
         switch matchedRuntime.contentType {
             case .package:
                 try await installFromPackage(dmgUrl: dmgUrl, runtime: matchedRuntime)
-            case .diskImage:
+            case .diskImage, .cryptexDiskImage:
                 try await installFromImage(dmgUrl: dmgUrl)
         }
         if shouldDelete {
@@ -183,7 +183,7 @@ public class RuntimeInstaller {
 
     @MainActor
     public func downloadOrUseExistingArchive(runtime: DownloadableRuntime, to destinationDirectory: Path, downloader: Downloader) async throws -> URL {
-        let url = URL(string: runtime.source)!
+        let url = runtime.sourceURL
         let destination = destinationDirectory/url.lastPathComponent
         let aria2DownloadMetadataPath = destination.parent/(destination.basename() + ".aria2")
         var aria2DownloadIsIncomplete = false
@@ -202,9 +202,7 @@ public class RuntimeInstaller {
             Current.logging.log("Found existing Runtime that will be used, at \(destination).")
             return destination.url
         }
-        if runtime.authentication == .virtual {
-            try await sessionService.validateADCSession(path: url.path).async()
-        }
+        try await sessionService.validateADCSession(path: url.path).async()
         let formatter = NumberFormatter(numberStyle: .percent)
         var observation: NSKeyValueObservation?
         let result = try await downloader.download(url: url, to: destination, progressChanged: { progress in
diff --git a/Tests/XcodesKitTests/RuntimeTests.swift b/Tests/XcodesKitTests/RuntimeTests.swift
index 314761a..fe6f135 100644
--- a/Tests/XcodesKitTests/RuntimeTests.swift
+++ b/Tests/XcodesKitTests/RuntimeTests.swift
@@ -171,7 +171,7 @@ final class RuntimeTests: XCTestCase {
         }
 
         let url = try await runtimeInstaller.downloadOrUseExistingArchive(runtime: runtime, to: .xcodesCaches, downloader: .urlSession)
-        let fileName = URL(string: runtime.source)!.lastPathComponent
+        let fileName = runtime.sourceURL.lastPathComponent
         XCTAssertEqual(url, Path.xcodesCaches.join(fileName).url)
         XCTAssertNil(xcodeDownloadURL)
     }
@@ -185,10 +185,10 @@ final class RuntimeTests: XCTestCase {
             return (Progress(), Promise.value((destination, HTTPURLResponse(url: url.pmkRequest.url!, statusCode: 200, httpVersion: nil, headerFields: nil)!)))
         }
         let runtime = try await runtimeList.downloadableRuntimes().downloadables.first { $0.visibleIdentifier == "iOS 15.5" }!
-        let fileName = URL(string: runtime.source)!.lastPathComponent
+        let fileName = runtime.sourceURL.lastPathComponent
         let url = try await runtimeInstaller.downloadOrUseExistingArchive(runtime: runtime, to: .xcodesCaches, downloader: .urlSession)
         XCTAssertEqual(url, Path.xcodesCaches.join(fileName).url)
-        XCTAssertEqual(xcodeDownloadURL, URL(string: runtime.source)!)
+        XCTAssertEqual(xcodeDownloadURL, runtime.sourceURL)
     }
 
     func test_installStepsForPackage() async throws {