diff --git a/experimental/collision/collision.go b/experimental/collision/collision.go
index 8227023a..d5bf643a 100644
--- a/experimental/collision/collision.go
+++ b/experimental/collision/collision.go
@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package collision implements collision related algorithms and data structures.
 package collision
 
 import "github.com/g3n/engine/geometry"
diff --git a/experimental/collision/doc.go b/experimental/collision/doc.go
new file mode 100644
index 00000000..4d77e29b
--- /dev/null
+++ b/experimental/collision/doc.go
@@ -0,0 +1,7 @@
+// Copyright 2016 The G3N Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package collision implements collision related algorithms and data structures.
+// WARNING: This package is experimental and incomplete!
+package collision
diff --git a/experimental/physics/doc.go b/experimental/physics/doc.go
index 5bf0a795..9b584e12 100644
--- a/experimental/physics/doc.go
+++ b/experimental/physics/doc.go
@@ -5,4 +5,3 @@
 // Package physics implements a basic physics engine.
 // WARNING: This package is experimental and incomplete!
 package physics
-