diff --git a/quic/core/quic_framer.cc b/quic/core/quic_framer.cc
index db6b867..010d478 100644
--- a/quic/core/quic_framer.cc
+++ b/quic/core/quic_framer.cc
@@ -872,9 +872,6 @@
     }
     return writer.length();
   }
-  // TODO(dschinazi) if we enable long header lengths before v99, we need to
-  // add support for fixing up lengths in QuicFramer::BuildDataPacket.
-  DCHECK(!QuicVersionHasLongHeaderLengths(transport_version()));
 
   size_t i = 0;
   for (const QuicFrame& frame : frames) {
@@ -1009,6 +1006,10 @@
     ++i;
   }
 
+  if (!WriteIetfLongHeaderLength(header, &writer, length_field_offset, level)) {
+    return 0;
+  }
+
   return writer.length();
 }
 
diff --git a/quic/core/quic_versions.h b/quic/core/quic_versions.h
index 98ffc2c..8a992ec 100644
--- a/quic/core/quic_versions.h
+++ b/quic/core/quic_versions.h
@@ -411,8 +411,6 @@
 // length field as defined by IETF QUIC draft-13 and later.
 QUIC_EXPORT_PRIVATE inline bool QuicVersionHasLongHeaderLengths(
     QuicTransportVersion transport_version) {
-  // TODO(dschinazi) if we enable long header lengths before v99, we need to
-  // add support for fixing up lengths in QuicFramer::BuildDataPacket.
   return transport_version == QUIC_VERSION_99;
 }