diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index a7f987a..2eb2fcc 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -467,6 +467,9 @@ int V4L2CameraProxy::vidioc_reqbufs(V4L2CameraFile *cf, struct v4l2_requestbuffe
 	memset(arg->reserved, 0, sizeof(arg->reserved));
 
 	if (arg->count == 0) {
+		if (!mmaps_.empty())
+			return -EBUSY;
+
 		if (vcam_->isRunning()) {
 			for (struct v4l2_buffer &buf : buffers_)
 				buf.flags &= ~(V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_DONE);