diff --git a/mfbt/ThreadLocal.h b/mfbt/ThreadLocal.h
index eaa187509d54b..1c0624267c70b 100644
--- a/mfbt/ThreadLocal.h
+++ b/mfbt/ThreadLocal.h
@@ -72,12 +72,17 @@ class ThreadLocal
     typedef pthread_key_t key_t;
 #endif
 
+    union Helper {
+      void *ptr;
+      T value;
+    };
+
   public:
     MOZ_WARN_UNUSED_RESULT inline bool init();
 
-    inline T* get() const;
+    inline T get() const;
 
-    inline bool set(const T* value);
+    inline bool set(const T value);
 
     bool initialized() const {
       return inited;
@@ -91,6 +96,7 @@ class ThreadLocal
 template <typename T>
 inline bool
 ThreadLocal<T>::init() {
+  MOZ_STATIC_ASSERT(sizeof(T) <= sizeof(void *), "mozilla::ThreadLocal can't be used for types larger than a pointer");
   MOZ_ASSERT(!initialized());
 #ifdef XP_WIN
   key = TlsAlloc();
@@ -102,24 +108,28 @@ ThreadLocal<T>::init() {
 }
 
 template <typename T>
-inline T*
+inline T
 ThreadLocal<T>::get() const {
   MOZ_ASSERT(initialized());
+  Helper h;
 #ifdef XP_WIN
-  return reinterpret_cast<T*>(TlsGetValue(key));
+  h.ptr = TlsGetValue(key);
 #else
-  return reinterpret_cast<T*>(pthread_getspecific(key));
+  h.ptr = pthread_getspecific(key);
 #endif
+  return h.value;
 }
 
 template <typename T>
 inline bool
-ThreadLocal<T>::set(const T* value) {
+ThreadLocal<T>::set(const T value) {
   MOZ_ASSERT(initialized());
+  Helper h;
+  h.value = value;
 #ifdef XP_WIN
-  return TlsSetValue(key, const_cast<T*>(value));
+  return TlsSetValue(key, h.ptr);
 #else
-  return !pthread_setspecific(key, value);
+  return !pthread_setspecific(key, h.ptr);
 #endif
 }
 
diff --git a/tools/profiler/TableTicker.cpp b/tools/profiler/TableTicker.cpp
index 17258b5f8b04a..42761e2bac23b 100644
--- a/tools/profiler/TableTicker.cpp
+++ b/tools/profiler/TableTicker.cpp
@@ -69,8 +69,8 @@ using namespace mozilla;
 #endif
 
 
-mozilla::ThreadLocal<ProfileStack> tlsStack;
-mozilla::ThreadLocal<TableTicker> tlsTicker;
+mozilla::ThreadLocal<ProfileStack *> tlsStack;
+mozilla::ThreadLocal<TableTicker *> tlsTicker;
 // We need to track whether we've been initialized otherwise
 // we end up using tlsStack without initializing it.
 // Because tlsStack is totally opaque to us we can't reuse
diff --git a/tools/profiler/sps_sampler.h b/tools/profiler/sps_sampler.h
index cc97bc068588c..219ae41942e58 100644
--- a/tools/profiler/sps_sampler.h
+++ b/tools/profiler/sps_sampler.h
@@ -17,8 +17,8 @@ using mozilla::TimeDuration;
 struct ProfileStack;
 class TableTicker;
 
-extern mozilla::ThreadLocal<ProfileStack> tlsStack;
-extern mozilla::ThreadLocal<TableTicker> tlsTicker;
+extern mozilla::ThreadLocal<ProfileStack *> tlsStack;
+extern mozilla::ThreadLocal<TableTicker *> tlsTicker;
 extern bool stack_key_initialized;
 
 #ifndef SAMPLE_FUNCTION_NAME