diff --git a/router/BUILD.bazel b/router/BUILD.bazel
index e0c562ce8e..f7fee76cd7 100644
--- a/router/BUILD.bazel
+++ b/router/BUILD.bazel
@@ -5,9 +5,9 @@ go_library(
     srcs = [
         "connector.go",
         "dataplane.go",
-        "serializeProxy.go",
         "fnv1aCheap.go",
         "metrics.go",
+        "serializeProxy.go",
         "svc.go",
     ],
     importpath = "github.com/scionproto/scion/router",
diff --git a/router/dataplane.go b/router/dataplane.go
index 2ce5a18740..57cb9ee108 100644
--- a/router/dataplane.go
+++ b/router/dataplane.go
@@ -2288,15 +2288,15 @@ func decodeSCMP(scmp *slayers.SCMP) ([]gopacket.SerializableLayer, error) {
 }
 
 // updateSCIONLayer rewrites the SCION header at the start of the given raw packet buffer; replacing
-// it with the serialization of the given new SCION header. This works only if the new header
-// is of the same size as the old one. This function has no knowledge of the actual size of the
-// headers; it only ensures that the new one ends exactly where the old one did. It is possible to
-// use this function to replace a header with a smaller one; but the preceding headers, and the
-// start of the slice must be corrected afterwards.
+// it with the serialization of the given new SCION header. This works only if the new header is of
+// the same size as the old one. This function has no knowledge of the actual size of the headers;
+// it only ensures that the new one ends exactly where the old one did. It is possible to use this
+// function to replace a header with a smaller one; but the rawPacket's slice must be fixed
+// afterwards (and the preceding headers, if any).
 func updateSCIONLayer(rawPkt []byte, s slayers.SCION) error {
 	payloadOffset := len(rawPkt) - len(s.LayerPayload())
 	serBuf := newSerializeProxy(rawPkt)
-	serBuf.clear(payloadOffset) // So, prepending just in front of the payload. Better not append!
+	serBuf.clear(payloadOffset) // Prepends will go just before payload. (Appends will wreck it)
 	return s.SerializeTo(&serBuf, gopacket.SerializeOptions{})
 }
 
@@ -2403,7 +2403,7 @@ func (b *bfdSend) Send(bfd *layers.BFD) error {
 		return err
 	}
 
-	// The usefull part of the buffer is given by Bytes. We don't copy the bytes; just the slice's
+	// The useful part of the buffer is given by Bytes. We don't copy the bytes; just the slice's
 	// metadata.
 	p.rawPacket = serBuf.Bytes()
 	if count < 10 {
diff --git a/router/serializeProxy.go b/router/serializeProxy.go
index e146d03298..96a355301d 100644
--- a/router/serializeProxy.go
+++ b/router/serializeProxy.go
@@ -27,7 +27,7 @@ import (
 type serializeProxy struct {
 	initStart int // Initial starting point (where the first prepend or append occurs)
 	data      []byte
-	start     int // data[0] == buf[0] (bc changing it is one way), so we keep track of the real start.
+	start     int // The slice's offset can't change (irreversible). So keep track separately.
 	layers    []gopacket.LayerType
 }
 
@@ -45,15 +45,15 @@ func newSerializeProxy(buf []byte) serializeProxy {
 // Resets the buffer to empty and sets the initial prepend/append point to the given position.
 func (s *serializeProxy) clear(newStart int) {
 	s.initStart = newStart
-	s.Clear()
+	s.start = newStart
+	s.data = s.data[:newStart]
+	s.layers = s.layers[:0]
 }
 
-// Implements serializeBuffer.Clear(). Never returns an error.
+// Implements serializeBuffer.Clear(). This implementation never returns an error.
 // The initial prepend/append point is reset to that which was set by the last call to clear().
 func (s *serializeProxy) Clear() error {
-	s.start = s.initStart
-	s.data = s.data[:s.start]
-	s.layers = s.layers[:0]
+	s.clear(s.initStart)
 	return nil
 }