diff --git a/lib/rac/rac_test.go b/lib/rac/rac_test.go
index d2903fb..a351d81 100644
--- a/lib/rac/rac_test.go
+++ b/lib/rac/rac_test.go
@@ -27,7 +27,11 @@
 
 const bytesPerHexDumpLine = 79
 
-const fakeCodec = Codec(0xEE)
+// fakeCodec is the codec used by this file's low level tests. The compressed
+// data is not actually in the Zlib format, but this Codec's value is
+// CodecZlib, since we need a valid Codec value, and CodecZlib is as good a
+// value as any other.
+const fakeCodec = CodecZlib
 
 var unhex = [256]uint8{
 	'0': 0x00, '1': 0x01, '2': 0x02, '3': 0x03, '4': 0x04,
@@ -66,9 +70,9 @@
 const writerWantILAEnd = "" +
 	"00000000  72 c3 63 00 52 72 72 53  73 41 61 61 42 62 62 62  |r.c.RrrSsAaaBbbb|\n" +
 	"00000010  43 63 63 63 63 63 63 63  63 63 31 32 72 c3 63 05  |Cccccccccc12r.c.|\n" +
-	"00000020  1d 45 00 ff 00 00 00 00  00 00 00 ff 00 00 00 00  |.E..............|\n" +
+	"00000020  2d 9a 00 ff 00 00 00 00  00 00 00 ff 00 00 00 00  |-...............|\n" +
 	"00000030  00 00 00 ff 11 00 00 00  00 00 00 ff 33 00 00 00  |............3...|\n" +
-	"00000040  00 00 00 01 77 00 00 00  00 00 00 ee 04 00 00 00  |....w...........|\n" +
+	"00000040  00 00 00 01 77 00 00 00  00 00 00 01 04 00 00 00  |....w...........|\n" +
 	"00000050  00 00 01 ff 07 00 00 00  00 00 01 ff 09 00 00 00  |................|\n" +
 	"00000060  00 00 01 ff 0c 00 00 00  00 00 01 00 10 00 00 00  |................|\n" +
 	"00000070  00 00 01 00 7c 00 00 00  00 00 01 05              |....|.......|\n"
@@ -76,17 +80,17 @@
 const writerWantILAEndCPageSize8 = "" +
 	"00000000  72 c3 63 00 52 72 72 00  53 73 41 61 61 00 00 00  |r.c.Rrr.SsAaa...|\n" +
 	"00000010  42 62 62 62 43 63 63 63  63 63 63 63 63 63 31 32  |BbbbCccccccccc12|\n" +
-	"00000020  72 c3 63 05 90 5e 00 ff  00 00 00 00 00 00 00 ff  |r.c..^..........|\n" +
+	"00000020  72 c3 63 05 a0 81 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
 	"00000030  00 00 00 00 00 00 00 ff  11 00 00 00 00 00 00 ff  |................|\n" +
-	"00000040  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 ee  |3.......w.......|\n" +
+	"00000040  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 01  |3.......w.......|\n" +
 	"00000050  04 00 00 00 00 00 01 ff  08 00 00 00 00 00 01 ff  |................|\n" +
 	"00000060  0a 00 00 00 00 00 01 ff  10 00 00 00 00 00 01 00  |................|\n" +
 	"00000070  14 00 00 00 00 00 01 00  80 00 00 00 00 00 01 05  |................|\n"
 
 const writerWantILAStart = "" +
-	"00000000  72 c3 63 05 bc dc 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
+	"00000000  72 c3 63 05 8c 03 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
 	"00000010  00 00 00 00 00 00 00 ff  11 00 00 00 00 00 00 ff  |................|\n" +
-	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 ee  |3.......w.......|\n" +
+	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 01  |3.......w.......|\n" +
 	"00000030  60 00 00 00 00 00 01 ff  63 00 00 00 00 00 01 ff  |`.......c.......|\n" +
 	"00000040  65 00 00 00 00 00 01 ff  68 00 00 00 00 00 01 00  |e.......h.......|\n" +
 	"00000050  6c 00 00 00 00 00 01 00  78 00 00 00 00 00 01 05  |l.......x.......|\n" +
@@ -94,9 +98,9 @@
 	"00000070  63 63 63 63 63 63 31 32                           |cccccc12|\n"
 
 const writerWantILAStartCPageSize4 = "" +
-	"00000000  72 c3 63 05 fc 4c 00 ff  00 00 00 00 00 00 00 ff  |r.c..L..........|\n" +
+	"00000000  72 c3 63 05 cc 93 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
 	"00000010  00 00 00 00 00 00 00 ff  11 00 00 00 00 00 00 ff  |................|\n" +
-	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 ee  |3.......w.......|\n" +
+	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 01  |3.......w.......|\n" +
 	"00000030  60 00 00 00 00 00 01 ff  64 00 00 00 00 00 01 ff  |`.......d.......|\n" +
 	"00000040  68 00 00 00 00 00 01 ff  6c 00 00 00 00 00 01 00  |h.......l.......|\n" +
 	"00000050  70 00 00 00 00 00 01 00  7c 00 00 00 00 00 01 05  |p.......|.......|\n" +
@@ -104,9 +108,9 @@
 	"00000070  43 63 63 63 63 63 63 63  63 63 31 32              |Cccccccccc12|\n"
 
 const writerWantILAStartCPageSize128 = "" +
-	"00000000  72 c3 63 05 d8 df 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
+	"00000000  72 c3 63 05 e8 00 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
 	"00000010  00 00 00 00 00 00 00 ff  11 00 00 00 00 00 00 ff  |................|\n" +
-	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 ee  |3.......w.......|\n" +
+	"00000020  33 00 00 00 00 00 00 01  77 00 00 00 00 00 00 01  |3.......w.......|\n" +
 	"00000030  80 00 00 00 00 00 01 ff  83 00 00 00 00 00 01 ff  |................|\n" +
 	"00000040  85 00 00 00 00 00 01 ff  88 00 00 00 00 00 01 00  |................|\n" +
 	"00000050  8c 00 00 00 00 00 01 00  98 00 00 00 00 00 01 05  |................|\n" +
@@ -306,10 +310,10 @@
 		gotHexDump[0x13C*bytesPerHexDumpLine:]
 
 	const wantHexDump = "" +
-		"00000000  72 c3 63 02 17 fa 00 fe  00 00 fc 00 00 00 00 fe  |r.c.............|\n" +
-		"00000010  00 00 04 01 00 00 00 ee  30 00 00 00 00 00 04 ff  |........0.......|\n" +
+		"00000000  72 c3 63 02 ec 35 00 fe  00 00 fc 00 00 00 00 fe  |r.c..5..........|\n" +
+		"00000010  00 00 04 01 00 00 00 01  30 00 00 00 00 00 04 ff  |........0.......|\n" +
 		"00000020  30 10 00 00 00 00 01 ff  e2 13 00 00 00 00 01 02  |0...............|\n" +
-		"00000030  72 c3 63 ff 4c be 00 ff  00 00 00 00 00 00 00 ff  |r.c.L...........|\n" +
+		"00000030  72 c3 63 ff 81 14 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
 		"00000040  00 00 00 00 00 00 00 ff  00 00 00 00 00 00 00 ff  |................|\n" +
 		"00000050  00 00 01 00 00 00 00 ff  00 00 02 00 00 00 00 ff  |................|\n" +
 		"00000060  00 00 03 00 00 00 00 01  00 00 04 00 00 00 00 02  |................|\n" +
@@ -317,7 +321,7 @@
 		"...\n" +
 		"00000800  00 00 f7 00 00 00 00 ff  00 00 f8 00 00 00 00 ff  |................|\n" +
 		"00000810  00 00 f9 00 00 00 00 ff  00 00 fa 00 00 00 00 ff  |................|\n" +
-		"00000820  00 00 fb 00 00 00 00 ff  00 00 fc 00 00 00 00 ee  |................|\n" +
+		"00000820  00 00 fb 00 00 00 00 ff  00 00 fc 00 00 00 00 01  |................|\n" +
 		"00000830  d9 10 00 00 00 00 01 ff  db 10 00 00 00 00 01 ff  |................|\n" +
 		"00000840  e0 10 00 00 00 00 01 ff  d0 10 00 00 00 00 01 ff  |................|\n" +
 		"00000850  d3 10 00 00 00 00 01 ff  d6 10 00 00 00 00 01 ff  |................|\n" +
@@ -327,11 +331,11 @@
 		"00001000  bb 13 00 00 00 00 01 ff  be 13 00 00 00 00 01 ff  |................|\n" +
 		"00001010  c1 13 00 00 00 00 01 ff  c4 13 00 00 00 00 01 ff  |................|\n" +
 		"00001020  c7 13 00 00 00 00 01 ff  e2 13 00 00 00 00 01 ff  |................|\n" +
-		"00001030  72 c3 63 09 f0 09 00 ff  00 00 00 00 00 00 00 ff  |r.c.............|\n" +
+		"00001030  72 c3 63 09 53 ad 00 ff  00 00 00 00 00 00 00 ff  |r.c.S...........|\n" +
 		"00001040  00 00 01 00 00 00 00 ff  00 00 02 00 00 00 00 ff  |................|\n" +
 		"00001050  00 00 03 00 00 00 00 ff  00 00 04 00 00 00 00 ff  |................|\n" +
 		"00001060  00 00 05 00 00 00 00 ff  00 00 06 00 00 00 00 ff  |................|\n" +
-		"00001070  00 00 07 00 00 00 00 ff  00 00 08 00 00 00 00 ee  |................|\n" +
+		"00001070  00 00 07 00 00 00 00 ff  00 00 08 00 00 00 00 01  |................|\n" +
 		"00001080  db 10 00 00 00 00 01 ff  ca 13 00 00 00 00 01 ff  |................|\n" +
 		"00001090  cd 13 00 00 00 00 01 ff  d0 13 00 00 00 00 01 ff  |................|\n" +
 		"000010a0  d3 13 00 00 00 00 01 ff  d6 13 00 00 00 00 01 ff  |................|\n" +