diff -ur madwifi.old/net80211/ieee80211_crypto_ccmp.c madwifi.dev/net80211/ieee80211_crypto_ccmp.c
--- madwifi.old/net80211/ieee80211_crypto_ccmp.c	2007-06-02 04:37:47.425966000 +0200
+++ madwifi.dev/net80211/ieee80211_crypto_ccmp.c	2007-06-02 18:38:27.675882768 +0200
@@ -465,6 +465,9 @@
 	uint8_t *mic, *pos;
 	u_int space;
 
+	if (ctx->cc_tfm == NULL)
+		return 0;
+
 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
 
 	skb = skb0;
@@ -579,6 +582,9 @@
 	uint8_t *pos, *mic;
 	u_int space;
 
+	if (ctx->cc_tfm == NULL)
+		return 0;
+
 	ctx->cc_vap->iv_stats.is_crypto_ccmp++;
 
 	skb = skb0;
diff -ur madwifi.old/net80211/ieee80211_crypto_ccmp.c madwifi.dev/net80211/ieee80211_crypto_ccmp.c
--- madwifi.old/net80211/ieee80211_crypto_ccmp.c	2007-06-02 19:40:56.291006648 +0200
+++ madwifi.dev/net80211/ieee80211_crypto_ccmp.c	2007-06-03 04:19:47.561334192 +0200
@@ -118,6 +118,12 @@
 	ctx->cc_ic = vap->iv_ic;
 	ctx->cc_tfm = crypto_alloc_cipher("aes", 0,
 					CRYPTO_ALG_ASYNC);
+	
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,18)
+	if (IS_ERR(ctx->cc_tfm))
+		ctx->cc_tfm = NULL;
+#endif
+
 	if (ctx->cc_tfm == NULL) {
 		IEEE80211_DPRINTF(vap, IEEE80211_MSG_CRYPTO,
 				"%s: unable to load kernel AES crypto support\n",