diff --git a/AppUpdater.swift b/AppUpdater.swift
index 1c9fbb9..b0452bf 100644
--- a/AppUpdater.swift
+++ b/AppUpdater.swift
@@ -762,8 +762,7 @@ struct Release: Decodable, Comparable {
         let prefix = "\(repo.lowercased())-"
         return assets.first { asset in
             let name = (asset.name as NSString).deletingPathExtension
-                .lowercased()
-            guard asset.contentType == .dmg, name.hasPrefix(prefix) else {
+            guard asset.contentType == .dmg, name.lowercased().hasPrefix(prefix) else {
                 return false
             }
             return Version(tolerant: name.dropFirst(prefix.count)) == tagName
diff --git a/Tests/AppUpdaterTests/AppUpdaterTests.swift b/Tests/AppUpdaterTests/AppUpdaterTests.swift
index 56bb186..df9f735 100644
--- a/Tests/AppUpdaterTests/AppUpdaterTests.swift
+++ b/Tests/AppUpdaterTests/AppUpdaterTests.swift
@@ -356,6 +356,18 @@ final class AppUpdaterTests: XCTestCase {
         }
     }
 
+    func testViableAssetPreservesPrereleaseCase() throws {
+        let matching = try release(
+            "v2.0.0-RC.1", prerelease: true, assetName: "APPUPDATER-2.0.0-RC.1.dmg"
+        )
+        XCTAssertEqual(matching.viableAsset(forRepo: "AppUpdater")?.name, "APPUPDATER-2.0.0-RC.1.dmg")
+
+        let mismatched = try release(
+            "v2.0.0-rc.1", prerelease: true, assetName: "AppUpdater-2.0.0-RC.1.dmg"
+        )
+        XCTAssertNil(mismatched.viableAsset(forRepo: "AppUpdater"))
+    }
+
     @MainActor
     func testCheckMatchesAssetNamedWithShortVersion() async throws {
         let releases = try [