diff --git a/include/llvm/System/ThreadLocal.h b/include/llvm/System/ThreadLocal.h
index 7627be26d2e..39b1e64be0c 100644
--- a/include/llvm/System/ThreadLocal.h
+++ b/include/llvm/System/ThreadLocal.h
@@ -24,8 +24,8 @@ namespace llvm {
     public:
       ThreadLocalImpl();
       virtual ~ThreadLocalImpl();
-      void setInstance(void* d);
-      void* getInstance();
+      void setInstance(const void* d);
+      const void* getInstance();
     };
     
     template<class T>
diff --git a/lib/System/ThreadLocal.cpp b/lib/System/ThreadLocal.cpp
index 74afa3e9538..f8b00d152a0 100644
--- a/lib/System/ThreadLocal.cpp
+++ b/lib/System/ThreadLocal.cpp
@@ -25,8 +25,8 @@ namespace llvm {
 using namespace sys;
 ThreadLocalImpl::ThreadLocalImpl() { }
 ThreadLocalImpl::~ThreadLocalImpl() { }
-void ThreadLocalImpl::setInstance(void* d) { data = d; }
-void* ThreadLocalImpl::getInstance() { return data; }
+void ThreadLocalImpl::setInstance(const void* d) { data = const_cast<void*>(d);}
+const void* ThreadLocalImpl::getInstance() { return data; }
 }
 #else
 
@@ -53,13 +53,13 @@ ThreadLocalImpl::~ThreadLocalImpl() {
   delete key;
 }
 
-void ThreadLocalImpl::setInstance(void* d) {
+void ThreadLocalImpl::setInstance(const void* d) {
   pthread_key_t* key = static_cast<pthread_key_t*>(data);
   int errorcode = pthread_setspecific(*key, d);
   assert(errorcode == 0);
 }
 
-void* ThreadLocalImpl::getInstance() {
+const void* ThreadLocalImpl::getInstance() {
   pthread_key_t* key = static_cast<pthread_key_t*>(data);
   return pthread_getspecific(*key);
 }
diff --git a/lib/System/Win32/ThreadLocal.inc b/lib/System/Win32/ThreadLocal.inc
index 5bba8b58f90..0ba3be451e6 100644
--- a/lib/System/Win32/ThreadLocal.inc
+++ b/lib/System/Win32/ThreadLocal.inc
@@ -35,12 +35,12 @@ ThreadLocalImpl::~ThreadLocalImpl() {
   delete tls;
 }
 
-void* ThreadLocalImpl::getInstance() {
+const void* ThreadLocalImpl::getInstance() {
   DWORD* tls = static_cast<DWORD*>(data);
   return TlsGetValue(*tls);
 }
 
-void ThreadLocalImpl::setInstance(void* d){
+void ThreadLocalImpl::setInstance(const void* d){
   DWORD* tls = static_cast<DWORD*>(data);
   int errorcode = TlsSetValue(*tls, d);
   assert(errorcode == 0);