diff --git a/TODO.markdown b/TODO.markdown
index 83142d7f..63c86049 100644
--- a/TODO.markdown
+++ b/TODO.markdown
@@ -10,7 +10,10 @@ need to be fixed.
 * Add tsig check in 'q'?
 * Tsig is handled in the library, api for querying tsig status
 * Query source address?
-* TEST nsec with TYPE65534
+
+* NSECx bitmap length
+  array of 256 block lens set to 0. scan RRs, save highest RR / 8 in
+  each block. len is 2 * # non-0 blocks + sum block len
 
 ## Examples to add
 
diff --git a/types.go b/types.go
index 3cd6d183..9abb8e68 100644
--- a/types.go
+++ b/types.go
@@ -642,9 +642,8 @@ func (rr *RR_NSEC) String() string {
 
 func (rr *RR_NSEC) Len() int {
 	l := len(rr.NextDomain) + 1
-	return rr.Hdr.Len() + l + len(rr.TypeBitMap) + 10
-	// TODO: + 10 is only there to be sure we have enough
-	// This is also shorter due to the windowing
+	return rr.Hdr.Len() + l + 32
+	// TODO: +32 is max type bitmap
 }
 
 type RR_DS struct {
@@ -859,9 +858,8 @@ func (rr *RR_NSEC3) String() string {
 }
 
 func (rr *RR_NSEC3) Len() int {
-	return rr.Hdr.Len() + 6 + len(rr.Salt)/2 + 1 + len(rr.NextDomain) + 1 + len(rr.TypeBitMap) + 10
-	// +10, see TODO for NSEC
-	// TODO: typebitmap length
+	return rr.Hdr.Len() + 6 + len(rr.Salt)/2 + 1 + len(rr.NextDomain) + 1 + 32
+	// TODO: +32 is MAX type bit map
 }
 
 type RR_NSEC3PARAM struct {