diff --git a/.travis.yml b/.travis.yml
index f659ab70ad..c24773b7b1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,6 +13,5 @@ install:
   - go get -v -t ./...
 
 script:
-  # `check_license` target is omitted due to some missing license headers
   # `staticcheck` target is omitted due to linting errors
-  - make style unused test
+  - make check_license style unused test
diff --git a/encoding_helpers.go b/encoding_helpers.go
index ffb58b5c8b..6dd6e7c2e4 100644
--- a/encoding_helpers.go
+++ b/encoding_helpers.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdb
 
 import (
diff --git a/fileutil/fileutil.go b/fileutil/fileutil.go
index 15403c8b3c..677df8c090 100644
--- a/fileutil/fileutil.go
+++ b/fileutil/fileutil.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 // Package fileutil provides utility methods used when dealing with the filesystem in tsdb.
 // It is largely copied from github.com/coreos/etcd/pkg/fileutil to avoid the
 // dependency chain it brings with it.
diff --git a/fileutil/mmap.go b/fileutil/mmap.go
index a0c598254e..26fc80c585 100644
--- a/fileutil/mmap.go
+++ b/fileutil/mmap.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package fileutil
 
 import (
diff --git a/fileutil/mmap_386.go b/fileutil/mmap_386.go
index 156f81b638..66b9d36803 100644
--- a/fileutil/mmap_386.go
+++ b/fileutil/mmap_386.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 // +build windows
 
 package fileutil
diff --git a/fileutil/mmap_amd64.go b/fileutil/mmap_amd64.go
index 4025dbfcb9..4b523bc67c 100644
--- a/fileutil/mmap_amd64.go
+++ b/fileutil/mmap_amd64.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 // +build windows
 
 package fileutil
diff --git a/head_bench_test.go b/head_bench_test.go
index 74341ad885..4b80193b29 100644
--- a/head_bench_test.go
+++ b/head_bench_test.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdb
 
 import (
diff --git a/index/encoding_helpers.go b/index/encoding_helpers.go
index 69e729791f..602498f115 100644
--- a/index/encoding_helpers.go
+++ b/index/encoding_helpers.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package index
 
 import (
diff --git a/repair.go b/repair.go
index be8c1f3ed6..fd40cbb5a9 100644
--- a/repair.go
+++ b/repair.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdb
 
 import (
diff --git a/repair_test.go b/repair_test.go
index 9a43a6d1d3..b3bf0acba3 100644
--- a/repair_test.go
+++ b/repair_test.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdb
 
 import (
diff --git a/tsdbutil/buffer.go b/tsdbutil/buffer.go
index 1a713166b7..dc2d960d23 100644
--- a/tsdbutil/buffer.go
+++ b/tsdbutil/buffer.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdbutil
 
 import (
diff --git a/tsdbutil/buffer_test.go b/tsdbutil/buffer_test.go
index d8db139a7f..0e3b8d045e 100644
--- a/tsdbutil/buffer_test.go
+++ b/tsdbutil/buffer_test.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdbutil
 
 import (
diff --git a/tsdbutil/chunks.go b/tsdbutil/chunks.go
index e3a8d0cc6e..e14d951ba2 100644
--- a/tsdbutil/chunks.go
+++ b/tsdbutil/chunks.go
@@ -1,3 +1,16 @@
+// Copyright 2018 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package tsdbutil
 
 import (