-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -I %S/Inputs/custom-modules -disable-availability-checking  %s -verify -verify-additional-file %swift_src_root/test/Inputs/clang-importer-sdk/usr/include/ObjCConcurrency.h -warn-concurrency
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -I %S/Inputs/custom-modules %s -verify -verify-additional-file %swift_src_root/test/Inputs/clang-importer-sdk/usr/include/ObjCConcurrency.h -warn-concurrency
 
 // REQUIRES: objc_interop
 // REQUIRES: concurrency
 import Foundation
 import ObjCConcurrency
+
+if #available(SwiftStdlib 5.5, *) {
 
 @MainActor func onlyOnMainActor() { }
 

  func takesSendable<T: Sendable>(_: T) {}

  takesSendable(sendableClass)        // no-error
  takesSendable(nonSendableClass)     // expected-FIXME-warning{{something about missing conformance}}

  doSomethingConcurrently {
    print(sendableClass)               // no-error

    }
  }
}

} // SwiftStdlib 5.5
