diff --git a/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc b/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
index 0e9e100..9643c7b 100644
--- a/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
+++ b/modules/audio_coding/codecs/red/audio_encoder_copy_red.cc
@@ -24,6 +24,8 @@
 static constexpr const int kRedMaxPacketSize =
     1 << 10;  // RED packets must be less than 1024 bytes to fit the 10 bit
               // block length.
+static constexpr const size_t kRedMaxTimestampDelta =
+    1 << 14;  // RED packets can encode a timestamp delta of 14 bits.
 static constexpr const size_t kAudioMaxRtpPacketLen =
     1200;  // The typical MTU is 1200 bytes.
 
@@ -100,7 +102,7 @@
   RTC_CHECK(info.redundant.empty()) << "Cannot use nested redundant encoders.";
   RTC_DCHECK_EQ(primary_encoded_.size(), info.encoded_bytes);
 
-  if (info.encoded_bytes == 0 || info.encoded_bytes > kRedMaxPacketSize) {
+  if (info.encoded_bytes == 0 || info.encoded_bytes >= kRedMaxPacketSize) {
     return info;
   }
   RTC_DCHECK_GT(max_packet_length_, info.encoded_bytes);
@@ -110,7 +112,9 @@
   auto it = redundant_encodings_.begin();
 
   // Determine how much redundancy we can fit into our packet by
-  // iterating forward.
+  // iterating forward. This is determined both by the length as well
+  // as the timestamp difference. The latter can occur with opus DTX which
+  // has timestamp gaps of 400ms which exceeds REDs timestamp delta field size.
   for (; it != redundant_encodings_.end(); it++) {
     if (bytes_available < kRedHeaderLength + it->first.encoded_bytes) {
       break;
@@ -118,6 +122,9 @@
     if (it->first.encoded_bytes == 0) {
       break;
     }
+    if (rtp_timestamp - it->first.encoded_timestamp >= kRedMaxTimestampDelta) {
+      break;
+    }
     bytes_available -= kRedHeaderLength + it->first.encoded_bytes;
     header_length_bytes += kRedHeaderLength;
   }
diff --git a/modules/audio_coding/codecs/red/audio_encoder_copy_red_unittest.cc b/modules/audio_coding/codecs/red/audio_encoder_copy_red_unittest.cc
index 168ac3a..0eeac01 100644
--- a/modules/audio_coding/codecs/red/audio_encoder_copy_red_unittest.cc
+++ b/modules/audio_coding/codecs/red/audio_encoder_copy_red_unittest.cc
@@ -583,6 +583,29 @@
   EXPECT_EQ(encoded_.size(), 5u + 500u + 400u);
 }
 
+TEST_F(AudioEncoderCopyRedTest, LargeTimestampGap) {
+  const int primary_payload_type = red_payload_type_ + 1;
+  AudioEncoder::EncodedInfo info;
+  info.encoded_bytes = 100;
+  info.encoded_timestamp = timestamp_;
+  info.payload_type = primary_payload_type;
+
+  EXPECT_CALL(*mock_encoder_, EncodeImpl(_, _, _))
+      .WillOnce(Invoke(MockAudioEncoder::FakeEncoding(info)));
+  Encode();
+  // Update timestamp to simulate a 400ms gap like the one
+  // opus DTX causes.
+  timestamp_ += 19200;
+  info.encoded_timestamp = timestamp_;  // update timestamp.
+  info.encoded_bytes = 200;
+  EXPECT_CALL(*mock_encoder_, EncodeImpl(_, _, _))
+      .WillOnce(Invoke(MockAudioEncoder::FakeEncoding(info)));
+  Encode();
+
+  // The old packet will be dropped.
+  EXPECT_EQ(encoded_.size(), 1u + 200u);
+}
+
 #if GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
 
 // This test fixture tests various error conditions that makes the