diff --git a/quic/core/frames/quic_ack_frame.cc b/quic/core/frames/quic_ack_frame.cc
index 72e806c..2946c01 100644
--- a/quic/core/frames/quic_ack_frame.cc
+++ b/quic/core/frames/quic_ack_frame.cc
@@ -89,19 +89,7 @@
     return;
   }
 
-  const auto new_interval = QuicInterval<QuicPacketNumber>(lower, higher);
-
-  if (!packet_number_intervals_.Empty() &&
-      packet_number_intervals_.SpanningInterval().Intersects(new_interval)) {
-    // TODO(wub): Remove this QUIC_BUG, or the AddRange method entirely.
-    // Ranges must be above or below all existing ranges.
-    QUIC_BUG << "AddRange only supports adding packets above or below the "
-             << "current min:" << Min() << " and max:" << Max()
-             << ", but adding [" << lower << "," << higher << ")";
-    return;
-  }
-
-  packet_number_intervals_.AddOptimizedForAppend(new_interval);
+  packet_number_intervals_.AddOptimizedForAppend(lower, higher);
 }
 
 bool PacketNumberQueue::RemoveUpTo(QuicPacketNumber higher) {
diff --git a/quic/core/frames/quic_ack_frame.h b/quic/core/frames/quic_ack_frame.h
index 18675a8..9003c76 100644
--- a/quic/core/frames/quic_ack_frame.h
+++ b/quic/core/frames/quic_ack_frame.h
@@ -36,8 +36,8 @@
   // Adds |packet_number| to the set of packets in the queue.
   void Add(QuicPacketNumber packet_number);
 
-  // Adds packets between [lower, higher) to the set of packets in the queue. It
-  // is undefined behavior to call this with |higher| < |lower|.
+  // Adds packets between [lower, higher) to the set of packets in the queue.
+  // No-op if |higher| < |lower|.
   // NOTE(wub): Only used in tests as of Nov 2019.
   void AddRange(QuicPacketNumber lower, QuicPacketNumber higher);
 
diff --git a/quic/core/frames/quic_frames_test.cc b/quic/core/frames/quic_frames_test.cc
index 63fe653..303fd0c 100644
--- a/quic/core/frames/quic_frames_test.cc
+++ b/quic/core/frames/quic_frames_test.cc
@@ -376,30 +376,27 @@
   EXPECT_EQ(QuicPacketNumber(1u), ack_frame1.packets.Min());
   EXPECT_EQ(QuicPacketNumber(99u), ack_frame1.packets.Max());
 
-  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals;
-  expected_intervals.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(1), QuicPacketNumber(10)));
-  expected_intervals.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(50), QuicPacketNumber(100)));
+  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals{
+      {QuicPacketNumber(1), QuicPacketNumber(10)},
+      {QuicPacketNumber(50), QuicPacketNumber(100)},
+  };
 
   const std::vector<QuicInterval<QuicPacketNumber>> actual_intervals(
       ack_frame1.packets.begin(), ack_frame1.packets.end());
 
   EXPECT_EQ(expected_intervals, actual_intervals);
 
-  // Ensure adding a range within the existing ranges fails.
-  EXPECT_QUIC_BUG(
-      ack_frame1.packets.AddRange(QuicPacketNumber(20), QuicPacketNumber(30)),
-      "");
+  // Add a range in the middle.
+  ack_frame1.packets.AddRange(QuicPacketNumber(20), QuicPacketNumber(30));
 
   const std::vector<QuicInterval<QuicPacketNumber>> actual_intervals2(
       ack_frame1.packets.begin(), ack_frame1.packets.end());
 
-  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals2;
-  expected_intervals2.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(1), QuicPacketNumber(10)));
-  expected_intervals2.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(50), QuicPacketNumber(100)));
+  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals2{
+      {QuicPacketNumber(1), QuicPacketNumber(10)},
+      {QuicPacketNumber(20), QuicPacketNumber(30)},
+      {QuicPacketNumber(50), QuicPacketNumber(100)},
+  };
 
   EXPECT_EQ(expected_intervals2.size(), ack_frame1.packets.NumIntervals());
   EXPECT_EQ(expected_intervals2, actual_intervals2);
@@ -415,17 +412,13 @@
   const std::vector<QuicInterval<QuicPacketNumber>> actual_intervals8(
       ack_frame2.packets.begin(), ack_frame2.packets.end());
 
-  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals8;
-  expected_intervals8.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(10), QuicPacketNumber(15)));
-  expected_intervals8.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(20), QuicPacketNumber(25)));
-  expected_intervals8.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(40), QuicPacketNumber(45)));
-  expected_intervals8.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(60), QuicPacketNumber(65)));
-  expected_intervals8.emplace_back(QuicInterval<QuicPacketNumber>(
-      QuicPacketNumber(80), QuicPacketNumber(85)));
+  std::vector<QuicInterval<QuicPacketNumber>> expected_intervals8{
+      {QuicPacketNumber(10), QuicPacketNumber(15)},
+      {QuicPacketNumber(20), QuicPacketNumber(25)},
+      {QuicPacketNumber(40), QuicPacketNumber(45)},
+      {QuicPacketNumber(60), QuicPacketNumber(65)},
+      {QuicPacketNumber(80), QuicPacketNumber(85)},
+  };
 
   EXPECT_EQ(expected_intervals8, actual_intervals8);
 }