Index: uspace/lib/ieee80211/include/ieee80211_private.h
===================================================================
--- uspace/lib/ieee80211/include/ieee80211_private.h	(revision 3767bdb1967dadcda1499dd3aa5304bc652f00a6)
+++ uspace/lib/ieee80211/include/ieee80211_private.h	(revision e71c023c4a684de0901f85c39d31d40c8f200ba7)
@@ -98,20 +98,14 @@
 
 /** Special room in header reserved for encryption. */
-typedef enum {
-	IEEE80211_TKIP_HEADER_LENGTH = 8,
-	IEEE80211_CCMP_HEADER_LENGTH = 8
-} ieee80211_encrypt_header_reserve_length_t;
+#define IEEE80211_TKIP_HEADER_LENGTH 8
+#define IEEE80211_CCMP_HEADER_LENGTH 8
 
 /** IEEE 802.11 PTK key length. */
-typedef enum {
-	IEEE80211_PTK_CCMP_LENGTH = 48,
-	IEEE80211_PTK_TKIP_LENGTH = 64
-} ieee80211_ptk_length_t;
+#define IEEE80211_PTK_CCMP_LENGTH 48
+#define IEEE80211_PTK_TKIP_LENGTH 64
 
 /** IEEE 802.11 GTK key length. */
-typedef enum {
-	IEEE80211_GTK_CCMP_LENGTH = 16,
-	IEEE80211_GTK_TKIP_LENGTH = 32
-} ieee80211_gtk_length_t;
+#define IEEE80211_GTK_CCMP_LENGTH 16
+#define IEEE80211_GTK_TKIP_LENGTH 32
 
 /** IEEE 802.11 frame types. */
Index: uspace/lib/ieee80211/src/ieee80211.c
===================================================================
--- uspace/lib/ieee80211/src/ieee80211.c	(revision 3767bdb1967dadcda1499dd3aa5304bc652f00a6)
+++ uspace/lib/ieee80211/src/ieee80211.c	(revision e71c023c4a684de0901f85c39d31d40c8f200ba7)
@@ -571,8 +571,10 @@
 	/* Init crypto data. */
 	bool add_mic = false;
+	const size_t max_head_space = max(IEEE80211_TKIP_HEADER_LENGTH,
+	    IEEE80211_CCMP_HEADER_LENGTH);
 	size_t head_space = 0, mic_space = 0;
 	uint16_t crypto = 0;
-	uint8_t head_data[head_space];
-	memset(head_data, 0, head_space);
+	uint8_t head_data[max_head_space];
+	memset(head_data, 0, max_head_space);
 
 	// TODO: Distinguish used key (pair/group) by dest address ?