diff --git a/talk/base/criticalsection.h b/talk/base/criticalsection.h
index c6ffbc0d9..92745ce77 100644
--- a/talk/base/criticalsection.h
+++ b/talk/base/criticalsection.h
@@ -29,6 +29,7 @@
 #define TALK_BASE_CRITICALSECTION_H__
 
 #include "talk/base/constructormagic.h"
+#include "webrtc/system_wrappers/interface/thread_annotations.h"
 
 #ifdef WIN32
 #include "talk/base/win32.h"
@@ -51,7 +52,7 @@
 namespace talk_base {
 
 #ifdef WIN32
-class CriticalSection {
+class LOCKABLE CriticalSection {
  public:
   CriticalSection() {
     InitializeCriticalSection(&crit_);
@@ -61,18 +62,18 @@ class CriticalSection {
   ~CriticalSection() {
     DeleteCriticalSection(&crit_);
   }
-  void Enter() {
+  void Enter() EXCLUSIVE_LOCK_FUNCTION() {
     EnterCriticalSection(&crit_);
     TRACK_OWNER(thread_ = GetCurrentThreadId());
   }
-  bool TryEnter() {
+  bool TryEnter() EXCLUSIVE_TRYLOCK_FUNCTION(true) {
     if (TryEnterCriticalSection(&crit_) != FALSE) {
       TRACK_OWNER(thread_ = GetCurrentThreadId());
       return true;
     }
     return false;
   }
-  void Leave() {
+  void Leave() UNLOCK_FUNCTION() {
     TRACK_OWNER(thread_ = 0);
     LeaveCriticalSection(&crit_);
   }
@@ -88,7 +89,7 @@ class CriticalSection {
 #endif // WIN32
 
 #ifdef POSIX
-class CriticalSection {
+class LOCKABLE CriticalSection {
  public:
   CriticalSection() {
     pthread_mutexattr_t mutex_attribute;
@@ -101,18 +102,18 @@ class CriticalSection {
   ~CriticalSection() {
     pthread_mutex_destroy(&mutex_);
   }
-  void Enter() {
+  void Enter() EXCLUSIVE_LOCK_FUNCTION()  {
     pthread_mutex_lock(&mutex_);
     TRACK_OWNER(thread_ = pthread_self());
   }
-  bool TryEnter() {
+  bool TryEnter() EXCLUSIVE_TRYLOCK_FUNCTION(true) {
     if (pthread_mutex_trylock(&mutex_) == 0) {
       TRACK_OWNER(thread_ = pthread_self());
       return true;
     }
     return false;
   }
-  void Leave() {
+  void Leave() UNLOCK_FUNCTION() {
     TRACK_OWNER(thread_ = 0);
     pthread_mutex_unlock(&mutex_);
   }
@@ -128,13 +129,13 @@ class CriticalSection {
 #endif // POSIX
 
 // CritScope, for serializing execution through a scope.
-class CritScope {
+class SCOPED_LOCKABLE CritScope {
  public:
-  explicit CritScope(CriticalSection *pcrit) {
+  explicit CritScope(CriticalSection *pcrit) EXCLUSIVE_LOCK_FUNCTION(pcrit) {
     pcrit_ = pcrit;
     pcrit_->Enter();
   }
-  ~CritScope() {
+  ~CritScope() UNLOCK_FUNCTION() {
     pcrit_->Leave();
   }
  private:
diff --git a/talk/base/sharedexclusivelock.h b/talk/base/sharedexclusivelock.h
index 2bdd85483..d06aa0101 100644
--- a/talk/base/sharedexclusivelock.h
+++ b/talk/base/sharedexclusivelock.h
@@ -36,14 +36,14 @@ namespace talk_base {
 
 // This class provides shared-exclusive lock. It can be used in cases like
 // multiple-readers/single-writer model.
-class SharedExclusiveLock {
+class LOCKABLE SharedExclusiveLock {
  public:
   SharedExclusiveLock();
 
   // Locking/unlocking methods. It is encouraged to use SharedScope or
   // ExclusiveScope for protection.
-  void LockExclusive();
-  void UnlockExclusive();
+  void LockExclusive() EXCLUSIVE_LOCK_FUNCTION();
+  void UnlockExclusive() UNLOCK_FUNCTION();
   void LockShared();
   void UnlockShared();
 
@@ -56,13 +56,14 @@ class SharedExclusiveLock {
   DISALLOW_COPY_AND_ASSIGN(SharedExclusiveLock);
 };
 
-class SharedScope {
+class SCOPED_LOCKABLE SharedScope {
  public:
-  explicit SharedScope(SharedExclusiveLock* lock) : lock_(lock) {
+  explicit SharedScope(SharedExclusiveLock* lock) SHARED_LOCK_FUNCTION(lock)
+      : lock_(lock) {
     lock_->LockShared();
   }
 
-  ~SharedScope() {
+  ~SharedScope() UNLOCK_FUNCTION() {
     lock_->UnlockShared();
   }
 
@@ -72,13 +73,15 @@ class SharedScope {
   DISALLOW_COPY_AND_ASSIGN(SharedScope);
 };
 
-class ExclusiveScope {
+class SCOPED_LOCKABLE ExclusiveScope {
  public:
-  explicit ExclusiveScope(SharedExclusiveLock* lock) : lock_(lock) {
+  explicit ExclusiveScope(SharedExclusiveLock* lock)
+      EXCLUSIVE_LOCK_FUNCTION(lock)
+      : lock_(lock) {
     lock_->LockExclusive();
   }
 
-  ~ExclusiveScope() {
+  ~ExclusiveScope() UNLOCK_FUNCTION() {
     lock_->UnlockExclusive();
   }
 
diff --git a/talk/base/signalthread.h b/talk/base/signalthread.h
index 46dd0a3ba..5865bf9fe 100644
--- a/talk/base/signalthread.h
+++ b/talk/base/signalthread.h
@@ -132,16 +132,17 @@ class SignalThread
     DISALLOW_IMPLICIT_CONSTRUCTORS(Worker);
   };
 
-  class EnterExit {
+  class SCOPED_LOCKABLE EnterExit {
    public:
-    explicit EnterExit(SignalThread* t) : t_(t) {
+    explicit EnterExit(SignalThread* t) EXCLUSIVE_LOCK_FUNCTION(t->cs_)
+        : t_(t) {
       t_->cs_.Enter();
       // If refcount_ is zero then the object has already been deleted and we
       // will be double-deleting it in ~EnterExit()! (shouldn't happen)
       ASSERT(t_->refcount_ != 0);
       ++t_->refcount_;
     }
-    ~EnterExit() {
+    ~EnterExit() UNLOCK_FUNCTION() {
       bool d = (0 == --t_->refcount_);
       t_->cs_.Leave();
       if (d)
diff --git a/talk/build/common.gypi b/talk/build/common.gypi
index 4c762d1dd..7bd1992d1 100644
--- a/talk/build/common.gypi
+++ b/talk/build/common.gypi
@@ -89,6 +89,7 @@
               # LateBindingSymbolTable::TableInfo from
               # latebindingsymboltable.cc.def and remove below flag.
               '-Wno-address-of-array-temporary',
+              '-Wthread-safety',
             ],
           }],
         ],
diff --git a/talk/session/media/mediamonitor.h b/talk/session/media/mediamonitor.h
index a9ce88959..7a416be77 100644
--- a/talk/session/media/mediamonitor.h
+++ b/talk/session/media/mediamonitor.h
@@ -77,7 +77,7 @@ class MediaMonitorT : public MediaMonitor {
     media_info_.Clear();
     media_channel_->GetStats(&media_info_);
   }
-  virtual void Update() {
+  virtual void Update() EXCLUSIVE_LOCKS_REQUIRED(crit_) {
     MI stats(media_info_);
     crit_.Leave();
     SignalUpdate(media_channel_, stats);