diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 2aff490..538d6b7 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1737,6 +1737,12 @@
 	local_bh_enable();
 }
 
+/*
+ * The TX headroom reserved by mac80211 for its own tx_status functions.
+ * This is enough for the radiotap header.
+ */
+#define IEEE80211_TX_STATUS_HEADROOM	13
+
 /**
  * ieee80211_tx_status - transmit status callback
  *
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 8116d1a..0d2d948 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -515,6 +515,8 @@
 	 * and we need some headroom for passing the frame to monitor
 	 * interfaces, but never both at the same time.
 	 */
+	BUILD_BUG_ON(IEEE80211_TX_STATUS_HEADROOM !=
+			sizeof(struct ieee80211_tx_status_rtap_hdr));
 	local->tx_headroom = max_t(unsigned int , local->hw.extra_tx_headroom,
 				   sizeof(struct ieee80211_tx_status_rtap_hdr));