diff --git a/smalltrip/problem/400.go b/smalltrip/problem/400.go
index 9f660cb..ba58622 100644
--- a/smalltrip/problem/400.go
+++ b/smalltrip/problem/400.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (
diff --git a/smalltrip/problem/500.go b/smalltrip/problem/500.go
index df6bd1b..6c5f285 100644
--- a/smalltrip/problem/500.go
+++ b/smalltrip/problem/500.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (
diff --git a/smalltrip/problem/handlers.go b/smalltrip/problem/handlers.go
index 8724412..42a847b 100644
--- a/smalltrip/problem/handlers.go
+++ b/smalltrip/problem/handlers.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (
diff --git a/smalltrip/problem/headers.go b/smalltrip/problem/headers.go
index aa5ee3a..54bbc81 100644
--- a/smalltrip/problem/headers.go
+++ b/smalltrip/problem/headers.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (
diff --git a/smalltrip/problem/middleware.go b/smalltrip/problem/middleware.go
index c51993c..c3870bf 100644
--- a/smalltrip/problem/middleware.go
+++ b/smalltrip/problem/middleware.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (
diff --git a/smalltrip/problem/problem.go b/smalltrip/problem/problem.go
index 7df9dca..4bd46a9 100644
--- a/smalltrip/problem/problem.go
+++ b/smalltrip/problem/problem.go
@@ -1,3 +1,18 @@
+// Copyright 2025-present Gustavo "Guz" L. de Mello
+// Copyright 2025-present The Lored.dev Contributors
+//
+// 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 problem
 
 import (