diff --git a/atomics/atomic_cas.cpp b/atomics/atomic_cas.cpp
new file mode 100644
index 0000000..ea62ffe
--- /dev/null
+++ b/atomics/atomic_cas.cpp
@@ -0,0 +1,38 @@
+
+#include <cassert>
+#include <atomic>
+#include "hc.hpp"
+#include "hc_am_internal.hpp"
+
+int main() {
+
+  constexpr unsigned long long init_value = 0;
+  constexpr unsigned long long new_value = 1234;
+
+  char* mem = hc::internal::am_alloc_host_coherent(sizeof(std::atomic_ullong));
+  std::atomic_ullong* a = new(mem) std::atomic_ullong(init_value);
+
+  hc::array_view<unsigned long long,1> av_old(1);
+  av_old[0] = 0xFFFFFFFFFFFFFFFF;
+
+  hc::array_view<bool> av_success(1);
+  av_success[0] = false;
+
+  hc::array_view<unsigned long long,1> av_load_after_cas(1);
+  av_load_after_cas[0] = 0xFFFFFFFFFFFFFFFF;
+
+  hc::parallel_for_each(hc::extent<1>(1), [=](hc::index<1> i) [[hc]] {
+    auto old = a->load();
+    av_old[0] = old;
+    auto success = a->compare_exchange_weak(old, new_value);
+    av_success[0] = success;
+    av_load_after_cas[0] = a->load();
+  }).wait();
+
+  assert(init_value == av_old[0]);
+  assert(av_success[0]);
+  assert(new_value == av_load_after_cas[0]);
+
+  hc::am_free(mem);
+  return 0;
+}