diff --git a/stepmania/src/RageThreads.cpp b/stepmania/src/RageThreads.cpp
index f3b4195f81..cddd94c8f3 100644
--- a/stepmania/src/RageThreads.cpp
+++ b/stepmania/src/RageThreads.cpp
@@ -30,6 +30,9 @@
 #endif
 #endif
 
+/* Assume TLS doesn't work until told otherwise.  It's ArchHooks's job to set this. */
+bool RageThread::m_bSystemSupportsTLS = false;
+
 #define MAX_THREADS 128
 //static vector<RageMutex*> *g_MutexList = NULL; /* watch out for static initialization order problems */
 
diff --git a/stepmania/src/RageThreads.h b/stepmania/src/RageThreads.h
index 526744c280..91fc9feb56 100644
--- a/stepmania/src/RageThreads.h
+++ b/stepmania/src/RageThreads.h
@@ -7,6 +7,8 @@ class RageThread
 	ThreadSlot *m_pSlot;
 	CString name;
 
+	static bool m_bSystemSupportsTLS;
+
 public:
 	RageThread();
 	~RageThread();
@@ -28,6 +30,13 @@ public:
 	static bool EnumThreadIDs( int n, uint64_t &iID );
 	int Wait();
 	bool IsCreated() const { return m_pSlot != NULL; }
+
+	/* A system can define HAVE_TLS, indicating that it can compile thread_local
+	 * code, but an individual environment may not actually have functional TLS.
+	 * If this returns false, thread_local variables are considered undefined. */
+	static bool GetSupportsTLS() { return m_bSystemSupportsTLS; }
+	
+	static void SetSupportsTLS( bool b ) { m_bSystemSupportsTLS = b; }
 };
 
 namespace Checkpoints