diff --git a/quic/api/QuicTransportFunctions.cpp b/quic/api/QuicTransportFunctions.cpp
index 46a141e93..99c5becb2 100644
--- a/quic/api/QuicTransportFunctions.cpp
+++ b/quic/api/QuicTransportFunctions.cpp
@@ -480,11 +480,12 @@ void updateConnection(
   bool retransmittable = false; // AckFrame and PaddingFrame are not retx-able.
   bool isHandshake = false;
   bool isPing = false;
-  bool isD6DProbe =
-      conn.d6d.lastProbe ? (packetNum == conn.d6d.lastProbe->packetNum) : false;
   uint32_t connWindowUpdateSent = 0;
   uint32_t ackFrameCounter = 0;
   auto packetNumberSpace = packet.header.getPacketNumberSpace();
+  bool isD6DProbe = packetNumberSpace == PacketNumberSpace::AppData &&
+      conn.d6d.lastProbe.hasValue() &&
+      conn.d6d.lastProbe->packetNum == packetNum;
   VLOG(10) << nodeToString(conn.nodeType) << " sent packetNum=" << packetNum
            << " in space=" << packetNumberSpace << " size=" << encodedSize
            << " " << conn;
diff --git a/quic/api/test/QuicTransportFunctionsTest.cpp b/quic/api/test/QuicTransportFunctionsTest.cpp
index 5de1e4339..8d7f85462 100644
--- a/quic/api/test/QuicTransportFunctionsTest.cpp
+++ b/quic/api/test/QuicTransportFunctionsTest.cpp
@@ -374,6 +374,18 @@ TEST_F(QuicTransportFunctionsTest, TestUpdateConnectionD6DNotConsumeSendPing) {
   EXPECT_TRUE(conn->pendingEvents.sendPing);
 }
 
+TEST_F(QuicTransportFunctionsTest, TestUpdateConnectionD6DNeedsAppDataPNSpace) {
+  auto conn = createConn();
+  auto packet = buildEmptyPacket(*conn, PacketNumberSpace::Handshake);
+  packet.packet.frames.push_back(PingFrame());
+  auto packetNum = packet.packet.header.getPacketSequenceNum();
+  conn->d6d.lastProbe = D6DProbePacket(packetNum, 50);
+  updateConnection(*conn, folly::none, packet.packet, Clock::now(), 50);
+  EXPECT_EQ(1, conn->outstandings.packets.size());
+  EXPECT_FALSE(conn->outstandings.packets.front().metadata.isD6DProbe);
+  EXPECT_EQ(0, conn->d6d.outstandingProbes);
+}
+
 TEST_F(QuicTransportFunctionsTest, TestUpdateConnectionPacketSorting) {
   auto conn = createConn();
   conn->qLogger = std::make_shared<quic::FileQLogger>(VantagePoint::Client);