diff --git a/wlantest/readpcap.c b/wlantest/readpcap.c
index 6c3853b05..1e7e66260 100644
--- a/wlantest/readpcap.c
+++ b/wlantest/readpcap.c
@@ -92,6 +92,7 @@ int read_cap_file(struct wlantest *wt, const char *fname)
 		}
 
 		/* Packet was read without problems */
+		wt->frame_num++;
 		wpa_printf(MSG_EXCESSIVE, "pcap hdr: ts=%d.%06d "
 			   "len=%u/%u",
 			   (int) hdr->ts.tv_sec, (int) hdr->ts.tv_usec,
diff --git a/wlantest/rx_data.c b/wlantest/rx_data.c
index f0f0df95c..d86a5886c 100644
--- a/wlantest/rx_data.c
+++ b/wlantest/rx_data.c
@@ -191,6 +191,23 @@ static u8 * try_all_ptk(struct wlantest *wt, int pairwise_cipher,
 }
 
 
+static void check_plaintext_prot(struct wlantest *wt,
+				 const struct ieee80211_hdr *hdr,
+				 const u8 *data, size_t len)
+{
+	if (len < 8 + 3 || data[8] != 0xaa || data[9] != 0xaa ||
+	    data[10] != 0x03)
+		return;
+
+	add_note(wt, MSG_DEBUG,
+		 "Plaintext payload in protected frame");
+	wpa_printf(MSG_INFO, "Plaintext payload in protected frame #%u: A2="
+		   MACSTR " seq=%u",
+		   wt->frame_num, MAC2STR(hdr->addr2),
+		   WLAN_GET_SEQ_SEQ(le_to_host16(hdr->seq_ctrl)));
+}
+
+
 static void rx_data_bss_prot_group(struct wlantest *wt,
 				   const struct ieee80211_hdr *hdr,
 				   size_t hdrlen,
@@ -241,6 +258,7 @@ static void rx_data_bss_prot_group(struct wlantest *wt,
 		}
 	}
 
+	check_plaintext_prot(wt, hdr, data, len);
 	keyid = data[3] >> 6;
 	if (bss->gtk_len[keyid] == 0 && bss->group_cipher != WPA_CIPHER_WEP40)
 	{
@@ -401,6 +419,7 @@ static void rx_data_bss_prot(struct wlantest *wt,
 			tdls = found;
 		}
 	}
+	check_plaintext_prot(wt, hdr, data, len);
 	if ((sta == NULL ||
 	     (!sta->ptk_set && sta->pairwise_cipher != WPA_CIPHER_WEP40)) &&
 	    tk == NULL) {
diff --git a/wlantest/wlantest.h b/wlantest/wlantest.h
index 2cf51966a..e2395d033 100644
--- a/wlantest/wlantest.h
+++ b/wlantest/wlantest.h
@@ -195,6 +195,7 @@ struct wlantest {
 	unsigned int rx_ctrl;
 	unsigned int rx_data;
 	unsigned int fcs_error;
+	unsigned int frame_num;
 
 	void *write_pcap; /* pcap_t* */
 	void *write_pcap_dumper; /* pcpa_dumper_t */