Index: uspace/lib/ieee80211/include/ieee80211_private.h
===================================================================
--- uspace/lib/ieee80211/include/ieee80211_private.h	(revision 158da11dad063cfb687cbd97022e4061037313db)
+++ uspace/lib/ieee80211/include/ieee80211_private.h	(revision f7eb18231e3df5c7521446e7da048d161e899bc4)
@@ -100,4 +100,6 @@
 #define IEEE80211_TKIP_HEADER_LENGTH 8
 #define IEEE80211_CCMP_HEADER_LENGTH 8
+/* Maximum of the above. */
+#define IEEE80211_MAX_HEADER_LENGTH 8
 
 /** IEEE 802.11 PTK key length. */
Index: uspace/lib/ieee80211/src/ieee80211.c
===================================================================
--- uspace/lib/ieee80211/src/ieee80211.c	(revision 158da11dad063cfb687cbd97022e4061037313db)
+++ uspace/lib/ieee80211/src/ieee80211.c	(revision f7eb18231e3df5c7521446e7da048d161e899bc4)
@@ -571,10 +571,8 @@
 	/* 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[max_head_space];
-	memset(head_data, 0, max_head_space);
+	uint8_t head_data[IEEE80211_MAX_HEADER_LENGTH];
+	memset(head_data, 0, sizeof(IEEE80211_MAX_HEADER_LENGTH));
 
 	// TODO: Distinguish used key (pair/group) by dest address ?