diff --git a/chunks/bstream.go b/chunks/bstream.go
index 26213374f..ed651db23 100644
--- a/chunks/bstream.go
+++ b/chunks/bstream.go
@@ -11,6 +11,34 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// The code in this file was largely written by Damian Gryski as part of
+// https://github.com/dgryski/go-tsz and published under the license below.
+// It received minor modifications to suit Prometheus's needs.
+
+// Copyright (c) 2015,2016 Damian Gryski <damian@gryski.com>
+// All rights reserved.
+
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+
+// * Redistributions of source code must retain the above copyright notice,
+// this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright notice,
+// this list of conditions and the following disclaimer in the documentation
+// and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 package chunks
 
 import "io"
diff --git a/chunks/xor.go b/chunks/xor.go
index cfbe09601..a72e9ef0c 100644
--- a/chunks/xor.go
+++ b/chunks/xor.go
@@ -11,10 +11,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// The code in this file was largely written by Damian Gryski and published
-// under the license below. It was modified to accomodate reading from byte
-// slice without modifying the underlying bytes, which would panick when reading
-// from mmaped read-only byte slices.
+// The code in this file was largely written by Damian Gryski as part of
+// https://github.com/dgryski/go-tsz and published under the license below.
+// It was modified to accomodate reading from byte slices without modifying
+// the underlying bytes, which would panic when reading from mmaped
+// read-only byte slices.
 
 // Copyright (c) 2015,2016 Damian Gryski <damian@gryski.com>
 // All rights reserved.