diff --git a/core/mac/inc/sir_mac_prot_def.h b/core/mac/inc/sir_mac_prot_def.h
index 95bba3b3e39b..5487dc38d413 100644
--- a/core/mac/inc/sir_mac_prot_def.h
+++ b/core/mac/inc/sir_mac_prot_def.h
@@ -561,7 +561,7 @@
 #define SIR_MAC_MAX_NUMBER_OF_RATES          12
 #define SIR_MAC_MAX_NUM_OF_DEFAULT_KEYS      4
 #define SIR_MAC_KEY_LENGTH                   13 /* WEP Maximum key length size */
-#define SIR_MAC_AUTH_CHALLENGE_LENGTH        128
+#define SIR_MAC_AUTH_CHALLENGE_LENGTH        253
 #define SIR_MAC_WEP_IV_LENGTH                4
 #define SIR_MAC_WEP_ICV_LENGTH               4