diff --git a/net/ieee80211/ieee80211_tx.c b/net/ieee80211/ieee80211_tx.c
index ae25449..854fc13 100644
--- a/net/ieee80211/ieee80211_tx.c
+++ b/net/ieee80211/ieee80211_tx.c
@@ -390,7 +390,7 @@
 		 * this stack is providing the full 802.11 header, one will
 		 * eventually be affixed to this fragment -- so we must account
 		 * for it when determining the amount of payload space. */
-		bytes_per_frag = frag_size - IEEE80211_3ADDR_LEN;
+		bytes_per_frag = frag_size - hdr_len;
 		if (ieee->config &
 		    (CFG_IEEE80211_COMPUTE_FCS | CFG_IEEE80211_RESERVE_FCS))
 			bytes_per_frag -= IEEE80211_FCS_LEN;
@@ -412,7 +412,7 @@
 	} else {
 		nr_frags = 1;
 		bytes_per_frag = bytes_last_frag = bytes;
-		frag_size = bytes + IEEE80211_3ADDR_LEN;
+		frag_size = bytes + hdr_len;
 	}
 
 	rts_required = (frag_size > ieee->rts