diff --git a/webrtc/test/vcm_capturer.cc b/webrtc/test/vcm_capturer.cc
index c37140f939..1c6b91915e 100644
--- a/webrtc/test/vcm_capturer.cc
+++ b/webrtc/test/vcm_capturer.cc
@@ -58,19 +58,25 @@ VcmCapturer* VcmCapturer::Create(VideoCaptureInput* input,
                                  size_t width,
                                  size_t height,
                                  size_t target_fps) {
-  VcmCapturer* vcm__capturer = new VcmCapturer(input);
-  if (!vcm__capturer->Init(width, height, target_fps)) {
+  VcmCapturer* vcm_capturer = new VcmCapturer(input);
+  if (!vcm_capturer->Init(width, height, target_fps)) {
     // TODO(pbos): Log a warning that this failed.
-    delete vcm__capturer;
+    delete vcm_capturer;
     return NULL;
   }
-  return vcm__capturer;
+  return vcm_capturer;
 }
 
 
-void VcmCapturer::Start() { started_ = true; }
+void VcmCapturer::Start() {
+  rtc::CritScope lock(&crit_);
+  started_ = true;
+}
 
-void VcmCapturer::Stop() { started_ = false; }
+void VcmCapturer::Stop() {
+  rtc::CritScope lock(&crit_);
+  started_ = false;
+}
 
 void VcmCapturer::Destroy() {
   if (vcm_ == NULL) {
@@ -90,6 +96,7 @@ VcmCapturer::~VcmCapturer() { Destroy(); }
 
 void VcmCapturer::OnIncomingCapturedFrame(const int32_t id,
                                           const VideoFrame& frame) {
+  rtc::CritScope lock(&crit_);
   if (started_)
     input_->IncomingCapturedFrame(frame);
 }
diff --git a/webrtc/test/vcm_capturer.h b/webrtc/test/vcm_capturer.h
index 93321f0ff1..53d61fc53a 100644
--- a/webrtc/test/vcm_capturer.h
+++ b/webrtc/test/vcm_capturer.h
@@ -10,6 +10,7 @@
 #ifndef WEBRTC_VIDEO_ENGINE_TEST_COMMON_VCM_CAPTURER_H_
 #define WEBRTC_VIDEO_ENGINE_TEST_COMMON_VCM_CAPTURER_H_
 
+#include "webrtc/base/criticalsection.h"
 #include "webrtc/common_types.h"
 #include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
 #include "webrtc/modules/video_capture/include/video_capture.h"
@@ -38,7 +39,8 @@ class VcmCapturer : public VideoCapturer, public VideoCaptureDataCallback {
   bool Init(size_t width, size_t height, size_t target_fps);
   void Destroy();
 
-  bool started_;
+  rtc::CriticalSection crit_;
+  bool started_ GUARDED_BY(crit_);
   VideoCaptureModule* vcm_;
   VideoCaptureCapability capability_;
 };