diff --git a/include/llvm/Support/ManagedStatic.h b/include/llvm/Support/ManagedStatic.h
index 4c1271cec74..e6384c72135 100644
--- a/include/llvm/Support/ManagedStatic.h
+++ b/include/llvm/Support/ManagedStatic.h
@@ -28,7 +28,7 @@ void object_deleter(void *Ptr) {
 /// ManagedStaticBase - Common base class for ManagedStatic instances.
 class ManagedStaticBase {
 protected:
-  sys::cas_flag InitFlag;
+  mutable sys::cas_flag InitFlag;
   
   // This should only be used as a static variable, which guarantees that this
   // will be zero initialized.
diff --git a/include/llvm/System/Atomic.h b/include/llvm/System/Atomic.h
index 2f95e0f7fbb..c6d59531917 100644
--- a/include/llvm/System/Atomic.h
+++ b/include/llvm/System/Atomic.h
@@ -55,10 +55,10 @@ namespace llvm {
       OSMemoryBarrier();
     }
     
-    typedef volatile UInt32 cas_flag;
+    typedef volatile int32_t cas_flag;
     inline cas_flag CompareAndSwap(cas_flag* dest, cas_flag exc, cas_flag c) {
       cas_flag old = *dest;
-      OSCompareAndSwap(c, exc, dest);
+      OSAtomicCompareAndSwap32(c, exc, dest);
       return old;
     }
 #elif defined(LLVM_ON_WIN32)