Index: lib/Fuzzer/FuzzerLoop.cpp
===================================================================
--- lib/Fuzzer/FuzzerLoop.cpp
+++ lib/Fuzzer/FuzzerLoop.cpp
@@ -431,11 +431,11 @@
   }
   // Returns true if there were more mallocs than frees.
   bool Stop() { return Mallocs > Frees; }
-  size_t Mallocs;
-  size_t Frees;
+  std::atomic<size_t> Mallocs;
+  std::atomic<size_t> Frees;
 };
 
-static thread_local MallocFreeTracer AllocTracer;
+static MallocFreeTracer AllocTracer;
 
 extern "C" {
 void __sanitizer_malloc_hook(void *ptr, size_t size) { AllocTracer.Mallocs++; }