diff --git a/src/nfc/tags/rw_t2t_ndef.cc b/src/nfc/tags/rw_t2t_ndef.cc
index 707f86b..d0edf39 100644
--- a/src/nfc/tags/rw_t2t_ndef.cc
+++ b/src/nfc/tags/rw_t2t_ndef.cc
@@ -601,6 +601,12 @@
               android_errorWriteLog(0x534e4554, "120506143");
             }
             if ((tlvtype == TAG_LOCK_CTRL_TLV) || (tlvtype == TAG_NDEF_TLV)) {
+              if (p_t2t->num_lockbytes > 0) {
+                LOG(ERROR) << StringPrintf("Malformed tag!");
+                android_errorWriteLog(0x534e4554, "147309942");
+                failed = true;
+                break;
+              }
               /* Collect Lock TLV */
               p_t2t->tlv_value[2 - p_t2t->bytes_count] = p_data[offset];
               if (p_t2t->bytes_count == 0) {