diff --git a/pkg/mapper/fsm/formatter.go b/pkg/mapper/fsm/formatter.go
index 591f9a8..d6782ba 100644
--- a/pkg/mapper/fsm/formatter.go
+++ b/pkg/mapper/fsm/formatter.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 fsm
 
 import (
diff --git a/pkg/mapper/fsm/fsm.go b/pkg/mapper/fsm/fsm.go
index 5a8f543..458c1b7 100644
--- a/pkg/mapper/fsm/fsm.go
+++ b/pkg/mapper/fsm/fsm.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 fsm
 
 import (
diff --git a/pkg/mapper/fsm/minmax.go b/pkg/mapper/fsm/minmax.go
index cf37159..95bd9c5 100644
--- a/pkg/mapper/fsm/minmax.go
+++ b/pkg/mapper/fsm/minmax.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 fsm
 
 // min and max implementation for integer