diff --git a/src/modules/audio_device/main/source/win/audio_device_core_win.cc b/src/modules/audio_device/main/source/win/audio_device_core_win.cc
index ab6a7ed7e..5589b6459 100644
--- a/src/modules/audio_device/main/source/win/audio_device_core_win.cc
+++ b/src/modules/audio_device/main/source/win/audio_device_core_win.cc
@@ -3568,6 +3568,16 @@ DWORD AudioDeviceWindowsCore::DoRenderThread()
         {
             _Lock();
 
+            // Sanity check to ensure that essential states are not modified
+            // during the unlocked period.
+            if (_ptrRenderClient == NULL || _ptrClientOut == NULL)
+            {
+                _UnLock();
+                WEBRTC_TRACE(kTraceCritical, kTraceAudioDevice, _id,
+                    "output state has been modified during unlocked period");
+                goto Exit;
+            }
+
             // Get the number of frames of padding (queued up to play) in the endpoint buffer.
             UINT32 padding = 0;
             hr = _ptrClientOut->GetCurrentPadding(&padding);
@@ -4016,6 +4026,16 @@ DWORD AudioDeviceWindowsCore::DoCaptureThread()
 
             _Lock();
 
+            // Sanity check to ensure that essential states are not modified
+            // during the unlocked period.
+            if (_ptrCaptureClient == NULL || _ptrClientIn == NULL)
+            {
+                _UnLock();
+                WEBRTC_TRACE(kTraceCritical, kTraceAudioDevice, _id,
+                    "input state has been modified during unlocked period");
+                goto Exit;
+            }
+
             //  Find out how much capture data is available
             //
             hr = _ptrCaptureClient->GetBuffer(&pData,           // packet which is ready to be read by used