diff --git a/libcxx/test/libcxx/input.output/filesystems/class.path/path.itr/iterator_db.pass.cpp b/libcxx/test/libcxx/input.output/filesystems/class.path/path.itr/iterator_db.pass.cpp
index 2729e59029bc3a..d5df253603c1a0 100644
--- a/libcxx/test/libcxx/input.output/filesystems/class.path/path.itr/iterator_db.pass.cpp
+++ b/libcxx/test/libcxx/input.output/filesystems/class.path/path.itr/iterator_db.pass.cpp
@@ -11,6 +11,9 @@
 
 // MODULES_DEFINES: _LIBCPP_DEBUG=0
 
+// This test requires debug mode, which the library on macOS doesn't have.
+// UNSUPPORTED: with_system_cxx_lib=macosx
+
 // <filesystem>
 
 // class path
diff --git a/libcxx/test/libcxx/thread/futures/futures.promise/set_exception.pass.cpp b/libcxx/test/libcxx/thread/futures/futures.promise/set_exception.pass.cpp
index b3621a4e697d0b..37ef0d1f04be8b 100644
--- a/libcxx/test/libcxx/thread/futures/futures.promise/set_exception.pass.cpp
+++ b/libcxx/test/libcxx/thread/futures/futures.promise/set_exception.pass.cpp
@@ -12,8 +12,8 @@
 
 // MODULES_DEFINES: _LIBCPP_DEBUG=0
 
-// Can't test the system lib because this test enables debug mode
-// UNSUPPORTED: with_system_cxx_lib
+// This test requires debug mode, which the library on macOS doesn't have.
+// UNSUPPORTED: with_system_cxx_lib=macosx
 
 // <future>
 
diff --git a/libcxx/test/libcxx/thread/futures/futures.promise/set_exception_at_thread_exit.pass.cpp b/libcxx/test/libcxx/thread/futures/futures.promise/set_exception_at_thread_exit.pass.cpp
index 49a41362db9a5f..54778777056c4b 100644
--- a/libcxx/test/libcxx/thread/futures/futures.promise/set_exception_at_thread_exit.pass.cpp
+++ b/libcxx/test/libcxx/thread/futures/futures.promise/set_exception_at_thread_exit.pass.cpp
@@ -12,8 +12,8 @@
 
 // MODULES_DEFINES: _LIBCPP_DEBUG=0
 
-// Can't test the system lib because this test enables debug mode
-// UNSUPPORTED: with_system_cxx_lib
+// This test requires debug mode, which the library on macOS doesn't have.
+// UNSUPPORTED: with_system_cxx_lib=macosx
 
 // <future>