diff --git a/webrtc/video_engine/vie_capturer.cc b/webrtc/video_engine/vie_capturer.cc
index 34c5754b55..0134c32001 100644
--- a/webrtc/video_engine/vie_capturer.cc
+++ b/webrtc/video_engine/vie_capturer.cc
@@ -53,8 +53,11 @@ class RegistrableCpuOveruseMetricsObserver : public CpuOveruseMetricsObserver {
   }
 
  private:
-  mutable rtc::CriticalSection crit_;
+  // TODO(pbos): Figure out why observer_ needs to be declared above crit_ on
+  // Mac. tommi@ also ran into this while debugging weird critical-section
+  // related alignment issues. Pushing this as a workaround to unblock rolling.
   CpuOveruseMetricsObserver* observer_ GUARDED_BY(crit_) = nullptr;
+  mutable rtc::CriticalSection crit_;
   CpuOveruseMetrics metrics_ GUARDED_BY(crit_);
 };