diff --git a/mingw-w64-crt/testcases/t_tls.cpp b/mingw-w64-crt/testcases/t_tls.cpp
new file mode 100755
index 0000000..eea2302
--- /dev/null
+++ b/mingw-w64-crt/testcases/t_tls.cpp
@@ -0,0 +1,47 @@
+/*
+ * tls.cpp
+ */
+
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <iostream>
+#include <process.h>
+
+
+int __thread tls_value = 0;
+
+unsigned __stdcall thread_fn(void*)
+{
+	++tls_value;
+	return 0;
+}
+
+// This is derived from the jig that I setup to explore the problems with
+// MT exception handling - you could probably just as easily set processors to
+// some value rather than tying it to the actual # of cores...
+int main()
+{
+	// Get the number of processors available to use
+	SYSTEM_INFO si;
+	GetSystemInfo(&si);
+	const unsigned processors = si.dwNumberOfProcessors;
+
+	// Make a thread for every processor and assign the thread to it
+    HANDLE threads[processors];
+    unsigned i;
+    for (i=0;i<processors;i++) {
+    	threads[i] = (HANDLE)_beginthreadex(0, 0, thread_fn, 0, CREATE_SUSPENDED, 0);
+    	SetThreadAffinityMask(threads[i], 1 << i);
+    }
+    // Restart all the threads
+    for (i=0;i<processors;i++)
+    	ResumeThread(threads[i]);
+    // Rejoin those threads
+	WaitForMultipleObjects(processors, threads, 1, INFINITE);
+	for (i=0;i<processors;i++)
+		CloseHandle(threads[i]);
+
+	std::cout << "How is it possible that tls_value is " << tls_value << " ?" << std::endl;
+
+	return 0;
+}