diff --git a/lib/rac/writer.go b/lib/rac/writer.go
index 1142b3f..c222fc6 100644
--- a/lib/rac/writer.go
+++ b/lib/rac/writer.go
@@ -115,6 +115,27 @@
 	b.p = len(b.prev)
 }
 
+// advancePastLeadingZeroes consumes the next n bytes, all of which are '\x00'.
+func (b *writeBuffer) advancePastLeadingZeroes() (n uint64) {
+	// Consume zeroes from b.prev.
+	i := b.p
+	for ; (i < len(b.prev)) && (b.prev[i] == '\x00'); i++ {
+	}
+	if i == b.p {
+		return 0
+	}
+	n = uint64(i - b.p)
+	b.p = i
+
+	// Consume zeroes from b.curr.
+	i = 0
+	for ; (i < len(b.curr)) && (b.curr[i] == '\x00'); i++ {
+	}
+	n += uint64(i)
+	b.curr = b.curr[i:]
+	return n
+}
+
 // compact moves and copies any unprocessed bytes in b.prev and b.curr to be at
 // the start of b.prev.
 func (b *writeBuffer) compact() {
@@ -371,6 +392,10 @@
 	if err := w.initialize(); err != nil {
 		return 0, err
 	}
+	if n := uint64(len(p)); (n > MaxSize) || (w.uncompressed.length() > (MaxSize - n)) {
+		w.err = errTooMuchInput
+		return 0, w.err
+	}
 	w.uncompressed.extend(p)
 	n, err := len(p), w.write(false)
 	w.uncompressed.compact()
@@ -494,11 +519,12 @@
 		}
 		fallthrough
 	case uint64(len(cBytes)) == w.cChunkSize:
+		w.uncompressed.advance(dSize)
+		dSize += w.uncompressed.advancePastLeadingZeroes()
 		if err := w.chunkWriter.AddChunk(dSize, cBytes, res2, res3, codec); err != nil {
 			w.err = err
 			return err
 		}
-		w.uncompressed.advance(dSize)
 		return nil
 	}
 
@@ -511,11 +537,13 @@
 		w.err = errCChunkSizeIsTooSmall
 		return w.err
 	}
-	if err := w.chunkWriter.AddChunk(uint64(dLen), cBytes[:eLen], res2, res3, codec); err != nil {
+	dSize, cBytes = uint64(dLen), cBytes[:eLen]
+	w.uncompressed.advance(dSize)
+	dSize += w.uncompressed.advancePastLeadingZeroes()
+	if err := w.chunkWriter.AddChunk(dSize, cBytes, res2, res3, codec); err != nil {
 		w.err = err
 		return err
 	}
-	w.uncompressed.advance(uint64(dLen))
 	return nil
 }
 
diff --git a/lib/raczlib/raczlib_test.go b/lib/raczlib/raczlib_test.go
index da6a4cb..c557f10 100644
--- a/lib/raczlib/raczlib_test.go
+++ b/lib/raczlib/raczlib_test.go
@@ -56,11 +56,12 @@
 		"\x28\x4A\x4D\x85\x71\x00\x01\x00\x00\xFF\xFF\x21\x6E\x04\x66"
 )
 
-func racCompress(original []byte, dChunkSize uint64, resourcesData [][]byte) ([]byte, error) {
+func racCompress(original []byte, cChunkSize uint64, dChunkSize uint64, resourcesData [][]byte) ([]byte, error) {
 	buf := &bytes.Buffer{}
 	w := &rac.Writer{
 		Writer:        buf,
 		CodecWriter:   &CodecWriter{},
+		CChunkSize:    cChunkSize,
 		DChunkSize:    dChunkSize,
 		ResourcesData: resourcesData,
 	}
@@ -175,35 +176,50 @@
 }
 
 func TestZeroedBytes(t *testing.T) {
-	original := []byte("abcde\x00\x00\x00\x00j")
-	compressed, err := racCompress(original, 8, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
+	original := make([]byte, 32)
+	original[0] = 'a'
+	original[1] = 'b'
+	original[2] = 'c'
+	original[20] = 'm'
+	original[31] = 'z'
 
-	r := &rac.Reader{
-		ReadSeeker:     bytes.NewReader(compressed),
-		CompressedSize: int64(len(compressed)),
-		CodecReaders:   []rac.CodecReader{&CodecReader{}},
-	}
-	for i := 0; i <= len(original); i++ {
-		want := original[i:]
-		got := make([]byte, len(want))
-		for j := range got {
-			got[j] = '?'
+	for i := 0; i < 2; i++ {
+		cChunkSize, dChunkSize := uint64(0), uint64(0)
+		if i == 0 {
+			cChunkSize = 10
+		} else {
+			dChunkSize = 8
 		}
 
-		if _, err := r.Seek(int64(i), io.SeekStart); err != nil {
-			t.Errorf("i=%d: Seek: %v", i, err)
-			continue
+		compressed, err := racCompress(original, cChunkSize, dChunkSize, nil)
+		if err != nil {
+			t.Fatalf("i=%d: racCompress: %v", i, err)
 		}
-		if _, err := io.ReadFull(r, got); err != nil {
-			t.Errorf("i=%d: ReadFull: %v", i, err)
-			continue
+
+		r := &rac.Reader{
+			ReadSeeker:     bytes.NewReader(compressed),
+			CompressedSize: int64(len(compressed)),
+			CodecReaders:   []rac.CodecReader{&CodecReader{}},
 		}
-		if !bytes.Equal(got, want) {
-			t.Errorf("i=%d: got\n% 02x\nwant\n% 02x", i, got, want)
-			continue
+		for j := 0; j <= len(original); j++ {
+			want := original[j:]
+			got := make([]byte, len(want))
+			for j := range got {
+				got[j] = '?'
+			}
+
+			if _, err := r.Seek(int64(j), io.SeekStart); err != nil {
+				t.Errorf("i=%d, j=%d: Seek: %v", i, j, err)
+				continue
+			}
+			if _, err := io.ReadFull(r, got); err != nil {
+				t.Errorf("i=%d, j=%d: ReadFull: %v", i, j, err)
+				continue
+			}
+			if !bytes.Equal(got, want) {
+				t.Errorf("i=%d, j=%d: got\n% 02x\nwant\n% 02x", i, j, got, want)
+				continue
+			}
 		}
 	}
 }
@@ -233,7 +249,7 @@
 		}
 
 		// Compress.
-		compressed, err := racCompress(original, n, resourcesData)
+		compressed, err := racCompress(original, 0, n, resourcesData)
 		if err != nil {
 			t.Fatalf("i=%d: racCompress: %v", i, err)
 		}