diff --git a/wlantest/gcmp.c b/wlantest/gcmp.c
index 5639b7e2b..d8535d0e2 100644
--- a/wlantest/gcmp.c
+++ b/wlantest/gcmp.c
@@ -73,7 +73,7 @@ static void gcmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
 }
 
 
-u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
+u8 * gcmp_decrypt(const u8 *tk, size_t tk_len, const struct ieee80211_hdr *hdr,
 		  const u8 *data, size_t data_len, size_t *decrypted_len)
 {
 	u8 aad[30], nonce[12], *plain;
@@ -95,7 +95,7 @@ u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 
-	if (aes_gcm_ad(tk, 16, nonce, sizeof(nonce), m, mlen, aad, aad_len,
+	if (aes_gcm_ad(tk, tk_len, nonce, sizeof(nonce), m, mlen, aad, aad_len,
 		       m + mlen, plain) < 0) {
 		u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
 		wpa_printf(MSG_INFO, "Invalid GCMP frame: A1=" MACSTR
@@ -113,7 +113,8 @@ u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 }
 
 
-u8 * gcmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
+u8 * gcmp_encrypt(const u8 *tk, size_t tk_len, u8 *frame, size_t len,
+		  size_t hdrlen, u8 *qos,
 		  u8 *pn, int keyid, size_t *encrypted_len)
 {
 	u8 aad[30], nonce[12], *crypt, *pos;
@@ -146,8 +147,8 @@ u8 * gcmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", aad, aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 
-	if (aes_gcm_ae(tk, 16, nonce, sizeof(nonce), frame + hdrlen, plen, aad,
-		       aad_len, pos, pos + plen) < 0) {
+	if (aes_gcm_ae(tk, tk_len, nonce, sizeof(nonce), frame + hdrlen, plen,
+		       aad, aad_len, pos, pos + plen) < 0) {
 		os_free(crypt);
 		return NULL;
 	}
diff --git a/wlantest/test_vectors.c b/wlantest/test_vectors.c
index 011620bd0..6a0283d3c 100644
--- a/wlantest/test_vectors.c
+++ b/wlantest/test_vectors.c
@@ -255,8 +255,8 @@ static void test_vector_gcmp(void)
 	wpa_hexdump(MSG_INFO, "802.11 Header", frame, 26);
 	wpa_hexdump(MSG_INFO, "Plaintext Data", frame + 26, sizeof(frame) - 26);
 
-	enc = gcmp_encrypt(tk, frame, sizeof(frame), 26, frame + 24, pn, 0,
-			   &enc_len);
+	enc = gcmp_encrypt(tk, sizeof(tk), frame, sizeof(frame), 26, frame + 24,
+			   pn, 0, &enc_len);
 	if (enc == NULL) {
 		wpa_printf(MSG_ERROR, "Failed to encrypt GCMP frame");
 		return;
@@ -267,7 +267,70 @@ static void test_vector_gcmp(void)
 	wpa_hexdump(MSG_INFO, "FCS", fcs, sizeof(fcs));
 
 	wpa_debug_level = MSG_INFO;
-	plain = gcmp_decrypt(tk, (const struct ieee80211_hdr *) enc,
+	plain = gcmp_decrypt(tk, sizeof(tk), (const struct ieee80211_hdr *) enc,
+			     enc + 26, enc_len - 26, &plain_len);
+	wpa_debug_level = MSG_EXCESSIVE;
+	os_free(enc);
+
+	if (plain == NULL) {
+		wpa_printf(MSG_ERROR, "Failed to decrypt GCMP frame");
+		return;
+	}
+
+	if (plain_len != sizeof(frame) - 26 ||
+	    os_memcmp(plain, frame + 26, plain_len) != 0) {
+		wpa_hexdump(MSG_ERROR, "Decryption result did not match",
+			    plain, plain_len);
+	}
+
+	os_free(plain);
+}
+
+
+static void test_vector_gcmp_256(void)
+{
+	u8 tk[] = { 0xc9, 0x7c, 0x1f, 0x67, 0xce, 0x37, 0x11, 0x85,
+		    0x51, 0x4a, 0x8a, 0x19, 0xf2, 0xbd, 0xd5, 0x2f,
+		    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+		    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
+	u8 pn[] = {
+		0x00, 0x89, 0x5F, 0x5F, 0x2B, 0x08
+	};
+	u8 frame[] = {
+		0x88, 0x48, 0x0b, 0x00, 0x0f, 0xd2, 0xe1, 0x28,
+		0xa5, 0x7c, 0x50, 0x30, 0xf1, 0x84, 0x44, 0x08,
+		0x50, 0x30, 0xf1, 0x84, 0x44, 0x08, 0x80, 0x33,
+		0x03, 0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05,
+		0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d,
+		0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
+		0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d,
+		0x1e, 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25,
+		0x26, 0x27
+	};
+	u8 *enc, *plain;
+	size_t enc_len, plain_len;
+	u8 fcs[4];
+
+	wpa_printf(MSG_INFO, "\nGCMP-256 test vector\n");
+
+	wpa_hexdump(MSG_INFO, "TK", tk, sizeof(tk));
+	wpa_hexdump(MSG_INFO, "PN", pn, sizeof(pn));
+	wpa_hexdump(MSG_INFO, "802.11 Header", frame, 26);
+	wpa_hexdump(MSG_INFO, "Plaintext Data", frame + 26, sizeof(frame) - 26);
+
+	enc = gcmp_encrypt(tk, sizeof(tk), frame, sizeof(frame), 26, frame + 24,
+			   pn, 0, &enc_len);
+	if (enc == NULL) {
+		wpa_printf(MSG_ERROR, "Failed to encrypt GCMP frame");
+		return;
+	}
+
+	wpa_hexdump(MSG_INFO, "Encrypted MPDU (without FCS)", enc, enc_len);
+	WPA_PUT_LE32(fcs, crc32(enc, enc_len));
+	wpa_hexdump(MSG_INFO, "FCS", fcs, sizeof(fcs));
+
+	wpa_debug_level = MSG_INFO;
+	plain = gcmp_decrypt(tk, sizeof(tk), (const struct ieee80211_hdr *) enc,
 			     enc + 26, enc_len - 26, &plain_len);
 	wpa_debug_level = MSG_EXCESSIVE;
 	os_free(enc);
@@ -300,6 +363,7 @@ int main(int argc, char *argv[])
 	test_vector_bip();
 	test_vector_ccmp_mgmt();
 	test_vector_gcmp();
+	test_vector_gcmp_256();
 
 	os_program_deinit();
 
diff --git a/wlantest/wlantest.h b/wlantest/wlantest.h
index be8f1f145..a2a0a6245 100644
--- a/wlantest/wlantest.h
+++ b/wlantest/wlantest.h
@@ -240,9 +240,10 @@ u8 * wep_decrypt(struct wlantest *wt, const struct ieee80211_hdr *hdr,
 u8 * bip_protect(const u8 *igtk, u8 *frame, size_t len, u8 *ipn, int keyid,
 		 size_t *prot_len);
 
-u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
+u8 * gcmp_decrypt(const u8 *tk, size_t tk_len, const struct ieee80211_hdr *hdr,
 		  const u8 *data, size_t data_len, size_t *decrypted_len);
-u8 * gcmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
+u8 * gcmp_encrypt(const u8 *tk, size_t tk_len, u8 *frame, size_t len,
+		  size_t hdrlen, u8 *qos,
 		  u8 *pn, int keyid, size_t *encrypted_len);
 
 int ctrl_init(struct wlantest *wt);