diff --git a/include/dwarfs/reader/internal/block_cache.h b/include/dwarfs/reader/internal/block_cache.h
index a737f347..075eb901 100644
--- a/include/dwarfs/reader/internal/block_cache.h
+++ b/include/dwarfs/reader/internal/block_cache.h
@@ -33,9 +33,6 @@
 
 namespace dwarfs {
 
-struct block_cache_options;
-struct cache_tidy_config;
-
 class logger;
 class mmif;
 class os_access;
@@ -47,7 +44,12 @@ class fs_section;
 
 }
 
-namespace reader::internal {
+namespace reader {
+
+struct block_cache_options;
+struct cache_tidy_config;
+
+namespace internal {
 
 class block_cache {
  public:
@@ -91,5 +93,6 @@ class block_cache {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace reader::internal
+} // namespace internal
+} // namespace reader
 } // namespace dwarfs
diff --git a/include/dwarfs/reader/internal/inode_reader_v2.h b/include/dwarfs/reader/internal/inode_reader_v2.h
index e61d786d..273a232d 100644
--- a/include/dwarfs/reader/internal/inode_reader_v2.h
+++ b/include/dwarfs/reader/internal/inode_reader_v2.h
@@ -35,14 +35,18 @@
 
 namespace dwarfs {
 
-struct cache_tidy_config;
-class block_cache;
 class logger;
-struct inode_reader_options;
-struct iovec_read_buf;
 class performance_monitor;
 
-namespace reader::internal {
+namespace reader {
+
+struct cache_tidy_config;
+struct inode_reader_options;
+struct iovec_read_buf;
+
+namespace internal {
+
+class block_cache;
 
 class inode_reader_v2 {
  public:
@@ -116,5 +120,6 @@ class inode_reader_v2 {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace reader::internal
+} // namespace internal
+} // namespace reader
 } // namespace dwarfs
diff --git a/include/dwarfs/reader/internal/metadata_v2.h b/include/dwarfs/reader/internal/metadata_v2.h
index 027b69a2..478a7ab9 100644
--- a/include/dwarfs/reader/internal/metadata_v2.h
+++ b/include/dwarfs/reader/internal/metadata_v2.h
@@ -42,10 +42,7 @@ namespace dwarfs {
 
 class logger;
 
-struct getattr_options;
-struct metadata_options;
 struct filesystem_info;
-struct fsinfo_options;
 struct vfs_stat;
 
 class performance_monitor;
@@ -54,7 +51,13 @@ namespace thrift::metadata {
 class metadata;
 }
 
-namespace reader::internal {
+namespace reader {
+
+struct fsinfo_options;
+struct getattr_options;
+struct metadata_options;
+
+namespace internal {
 
 class metadata_v2 {
  public:
@@ -250,5 +253,6 @@ class metadata_v2 {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace reader::internal
+} // namespace internal
+} // namespace reader
 } // namespace dwarfs
diff --git a/include/dwarfs/writer/internal/file_scanner.h b/include/dwarfs/writer/internal/file_scanner.h
index e2d9f860..86f9afbf 100644
--- a/include/dwarfs/writer/internal/file_scanner.h
+++ b/include/dwarfs/writer/internal/file_scanner.h
@@ -31,15 +31,17 @@ namespace dwarfs {
 class logger;
 class os_access;
 
-struct inode_options;
-
 namespace internal {
 
 class worker_group;
 
 } // namespace internal
 
-namespace writer::internal {
+namespace writer {
+
+struct inode_options;
+
+namespace internal {
 
 class file;
 class inode_manager;
@@ -75,6 +77,6 @@ class file_scanner {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace writer::internal
-
+} // namespace internal
+} // namespace writer
 } // namespace dwarfs
diff --git a/include/dwarfs/writer/internal/global_entry_data.h b/include/dwarfs/writer/internal/global_entry_data.h
index d1fb100f..a4d182d9 100644
--- a/include/dwarfs/writer/internal/global_entry_data.h
+++ b/include/dwarfs/writer/internal/global_entry_data.h
@@ -30,11 +30,11 @@
 
 #include <dwarfs/file_stat.h>
 
-namespace dwarfs {
+namespace dwarfs::writer {
 
 struct scanner_options;
 
-namespace writer::internal {
+namespace internal {
 
 class global_entry_data {
  public:
@@ -109,6 +109,5 @@ class global_entry_data {
   scanner_options const& options_;
 };
 
-} // namespace writer::internal
-
-} // namespace dwarfs
+} // namespace internal
+} // namespace dwarfs::writer
diff --git a/include/dwarfs/writer/internal/inode.h b/include/dwarfs/writer/internal/inode.h
index e3891700..72315361 100644
--- a/include/dwarfs/writer/internal/inode.h
+++ b/include/dwarfs/writer/internal/inode.h
@@ -46,9 +46,11 @@ class chunk;
 class mmif;
 class os_access;
 
+namespace writer {
+
 struct inode_options;
 
-namespace writer::internal {
+namespace internal {
 
 class file;
 class progress;
@@ -85,6 +87,6 @@ class inode : public object {
 using sortable_inode_span =
     sortable_span<std::shared_ptr<inode> const, uint32_t>;
 
-} // namespace writer::internal
-
+} // namespace internal
+} // namespace writer
 } // namespace dwarfs
diff --git a/include/dwarfs/writer/internal/inode_manager.h b/include/dwarfs/writer/internal/inode_manager.h
index 6605af14..da1e70db 100644
--- a/include/dwarfs/writer/internal/inode_manager.h
+++ b/include/dwarfs/writer/internal/inode_manager.h
@@ -38,15 +38,17 @@ namespace dwarfs {
 class logger;
 class os_access;
 
-struct inode_options;
-
 namespace internal {
 
 class worker_group;
 
 }
 
-namespace writer::internal {
+namespace writer {
+
+struct inode_options;
+
+namespace internal {
 
 class file;
 class progress;
@@ -134,6 +136,6 @@ class inode_manager {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace writer::internal
-
+} // namespace internal
+} // namespace writer
 } // namespace dwarfs
diff --git a/include/dwarfs/writer/internal/inode_ordering.h b/include/dwarfs/writer/internal/inode_ordering.h
index 19f35e9b..97ca2ac5 100644
--- a/include/dwarfs/writer/internal/inode_ordering.h
+++ b/include/dwarfs/writer/internal/inode_ordering.h
@@ -27,8 +27,6 @@
 
 namespace dwarfs {
 
-struct inode_options;
-
 class logger;
 
 namespace internal {
@@ -37,7 +35,11 @@ class worker_group;
 
 }
 
-namespace writer::internal {
+namespace writer {
+
+struct inode_options;
+
+namespace internal {
 
 class progress;
 
@@ -86,6 +88,6 @@ class inode_ordering {
   std::unique_ptr<impl> impl_;
 };
 
-} // namespace writer::internal
-
+} // namespace internal
+} // namespace writer
 } // namespace dwarfs
diff --git a/include/dwarfs/writer/scanner.h b/include/dwarfs/writer/scanner.h
index 39faed09..35f84937 100644
--- a/include/dwarfs/writer/scanner.h
+++ b/include/dwarfs/writer/scanner.h
@@ -30,7 +30,6 @@
 namespace dwarfs {
 
 class file_access;
-class filesystem_writer;
 class logger;
 class os_access;
 class thread_pool;
@@ -42,6 +41,7 @@ struct scanner_options;
 class entry_filter;
 class entry_transformer;
 class entry_factory;
+class filesystem_writer;
 class writer_progress;
 class segmenter_factory;
 
@@ -88,5 +88,4 @@ class scanner {
 };
 
 } // namespace writer
-
 } // namespace dwarfs