--- a/dom/media/webrtc/MediaEngineRemoteVideoSource.cpp
+++ b/dom/media/webrtc/MediaEngineRemoteVideoSource.cpp
@@ -312,16 +312,17 @@ MediaEngineRemoteVideoSource::UpdateSing
                                   aHandle->mPrincipalInfo)) {
         return NS_ERROR_FAILURE;
       }
       mState = kAllocated;
       SetLastCapability(mCapability);
       LOG(("Video device %d allocated", mCaptureIndex));
       break;
 
+    case kAllocated:
     case kStarted:
       {
         size_t index = mHandleIds.NoIndex;
         if (aHandle) {
           mHandleId = aHandle->mId;
           index = mHandleIds.IndexOf(mHandleId);
         }
 
@@ -346,23 +347,25 @@ MediaEngineRemoteVideoSource::UpdateSing
         if (!ChooseCapability(aNetConstraints, aPrefs, aDeviceId, mCapability,
                               kFeasibility)) {
           *aOutBadConstraint = FindBadConstraint(aNetConstraints, *this, aDeviceId);
           return NS_ERROR_FAILURE;
         }
         LOG(("ChooseCapability(kFeasibility) for mCapability --"));
 
         if (mCapability != mLastCapability) {
-          camera::GetChildAndCall(&camera::CamerasChild::StopCapture,
-                                  mCapEngine, mCaptureIndex);
-          if (camera::GetChildAndCall(&camera::CamerasChild::StartCapture,
-                                      mCapEngine, mCaptureIndex, mCapability,
-                                      this)) {
-            LOG(("StartCapture failed"));
-            return NS_ERROR_FAILURE;
+          if (mState == kStarted) {
+            camera::GetChildAndCall(&camera::CamerasChild::StopCapture,
+                                    mCapEngine, mCaptureIndex);
+            if (camera::GetChildAndCall(&camera::CamerasChild::StartCapture,
+                                        mCapEngine, mCaptureIndex, mCapability,
+                                        this)) {
+              LOG(("StartCapture failed"));
+              return NS_ERROR_FAILURE;
+            }
           }
           SetLastCapability(mCapability);
         }
         break;
       }
 
     default:
       LOG(("Video device %d in ignored state %d", mCaptureIndex, mState));