diff --git a/src/file/chunks.odin b/src/file/chunks.odin
index 0a98313..07935f8 100644
--- a/src/file/chunks.odin
+++ b/src/file/chunks.odin
@@ -29,25 +29,44 @@ AssetIndex :: struct #packed #all_or_none {
 	offset:  u64,
 }
 
-Offsets :: struct {
+AssetTable :: struct {
 	asset_index_offset: u64,
 	data_offset:        u64,
 	asset_offsets:      [dynamic]u64,
 	asset_sizes:        [dynamic]u64,
 }
 
-// -----------------------------------------
-
-@(private)
-offsets: Offsets
+Writer :: struct {
+	chunk_file:  ^os.File,
+	asset_file:  ^os.File,
+	asset_table: AssetTable,
+}
 
 // -----------------------------------------
 
-compute_metadata_offsets :: proc(number_of_assets: u64) {
+writer_init :: proc(
+	number_of_assets: u64,
+	allocator := context.allocator,
+) -> (
+	w: Writer,
+	err: runtime.Allocator_Error,
+) #optional_allocator_error {
 	// [ Header ][ []Asset Index ][ Data ]
-	offsets.asset_index_offset = size_of(Header)
-	offsets.data_offset =
+	w.asset_table.asset_index_offset = size_of(Header)
+	w.asset_table.data_offset =
 		size_of(Header) + (size_of(AssetIndex) * number_of_assets)
+	w.asset_table.asset_offsets = make([dynamic]u64, allocator) or_return
+	w.asset_table.asset_sizes = make([dynamic]u64, allocator) or_return
+	resize(&w.asset_table.asset_offsets, number_of_assets)
+	resize(&w.asset_table.asset_sizes, number_of_assets)
+	return w, nil
+}
+
+writer_destroy :: proc(w: ^Writer) {
+	if w.chunk_file != nil do os.close(w.chunk_file)
+	if w.asset_file != nil do os.close(w.asset_file)
+	delete(w.asset_table.asset_offsets)
+	delete(w.asset_table.asset_sizes)
 }
 
 @(private)
@@ -71,8 +90,3 @@ compute_chunk_path :: proc(
 
 	return chunk_path // owning string
 }
-
-delete_offsets :: proc() {
-	delete(offsets.asset_offsets)
-	delete(offsets.asset_sizes)
-}
diff --git a/src/file/write_assets.odin b/src/file/write_assets.odin
index 0c8b436..7d03a88 100644
--- a/src/file/write_assets.odin
+++ b/src/file/write_assets.odin
@@ -7,15 +7,8 @@ import "core:os"
 
 // -----------------------------------------
 
-@(private = "file")
-chunk_file: ^os.File
-
-@(private = "file")
-asset_file: ^os.File
-
-// -----------------------------------------
-
 write_assets :: proc(
+	w: ^Writer,
 	output: ^os.File,
 	entries: []FileEntry,
 	size_per_chunk: u64 = SIZE_PER_CHUNK,
@@ -27,15 +20,13 @@ write_assets :: proc(
 	asset_index := 0
 	chunk_offset: u64 = 0
 	asset_offset: u64 = 0
-	total_offset: u64 = offsets.data_offset
+	total_offset: u64 = w.asset_table.data_offset
 	number_of_assets := len(entries)
-	resize(&offsets.asset_offsets, number_of_assets)
-	resize(&offsets.asset_sizes, number_of_assets)
 
-	if size_per_chunk < offsets.data_offset {
+	if size_per_chunk < w.asset_table.data_offset {
 		fmt.eprintln(
 			"error: chunk size too small to hold asset index:",
-			offsets.data_offset,
+			w.asset_table.data_offset,
 		)
 		os.exit(1)
 	}
@@ -43,25 +34,25 @@ write_assets :: proc(
 	// ----------------------------------------
 
 	// Create new chunk
-	chunk_stream := create_new_chunk(output_path, chunk_index, allocator)
+	chunk_stream := create_new_chunk(w, output_path, chunk_index, allocator)
 
 	// Edge case of the chunk size being exactly the size of the data offset
-	if size_per_chunk == offsets.data_offset {
+	if size_per_chunk == w.asset_table.data_offset {
 		chunk_index += 1
-		chunk_stream = create_new_chunk(output_path, chunk_index, allocator)
+		chunk_stream = create_new_chunk(w, output_path, chunk_index, allocator)
 	}
 
 	// Chunk 0 starts after metadata
 	if (chunk_index == 0) {
-		chunk_offset = offsets.data_offset
+		chunk_offset = w.asset_table.data_offset
 	}
 
 	// ----------------------------------------
 
 	// Open asset
-	asset_stream, asset_size := open_asset(entries[asset_index].relpath)
-	offsets.asset_offsets[asset_index] = total_offset
-	offsets.asset_sizes[asset_index] = asset_size
+	asset_stream, asset_size := open_asset(w, entries[asset_index].relpath)
+	w.asset_table.asset_offsets[asset_index] = total_offset
+	w.asset_table.asset_sizes[asset_index] = asset_size
 
 	// ----------------------------------------
 
@@ -83,9 +74,12 @@ write_assets :: proc(
 			asset_index += 1
 			asset_offset = 0
 			if asset_index == number_of_assets do break
-			asset_stream, asset_size = open_asset(entries[asset_index].relpath)
-			offsets.asset_offsets[asset_index] = total_offset
-			offsets.asset_sizes[asset_index] = asset_size
+			asset_stream, asset_size = open_asset(
+				w,
+				entries[asset_index].relpath,
+			)
+			w.asset_table.asset_offsets[asset_index] = total_offset
+			w.asset_table.asset_sizes[asset_index] = asset_size
 
 		} else if asset_remaining == chunk_remaining {
 
@@ -97,14 +91,18 @@ write_assets :: proc(
 			asset_index += 1
 			asset_offset = 0
 			if asset_index == number_of_assets do break
-			asset_stream, asset_size = open_asset(entries[asset_index].relpath)
-			offsets.asset_offsets[asset_index] = total_offset
-			offsets.asset_sizes[asset_index] = asset_size
+			asset_stream, asset_size = open_asset(
+				w,
+				entries[asset_index].relpath,
+			)
+			w.asset_table.asset_offsets[asset_index] = total_offset
+			w.asset_table.asset_sizes[asset_index] = asset_size
 
 			// Create new chunk
 			chunk_index += 1
 			chunk_offset = 0
 			chunk_stream = create_new_chunk(
+				w,
 				output_path,
 				chunk_index,
 				allocator,
@@ -118,22 +116,18 @@ write_assets :: proc(
 			chunk_index += 1
 			chunk_offset = 0
 			chunk_stream = create_new_chunk(
+				w,
 				output_path,
 				chunk_index,
 				allocator,
 			)
 		}
 	}
-
-	// ----------------------------------------
-
-	// Cleaup leftover
-	os.close(chunk_file)
-	os.close(asset_file)
 }
 
 @(private)
 create_new_chunk :: proc(
+	w: ^Writer,
 	output_path: string,
 	chunk_index: int,
 	allocator: runtime.Allocator,
@@ -149,24 +143,24 @@ create_new_chunk :: proc(
 		}
 	}
 
-	if chunk_file != nil do os.close(chunk_file) // close previous
+	if w.chunk_file != nil do os.close(w.chunk_file) // close previous
 
 	// Create new chunk
 	cf_err: os.Error
-	chunk_file, cf_err = os.create(chunk_path)
+	w.chunk_file, cf_err = os.create(chunk_path)
 	if cf_err != nil {
 		fmt.eprintln("error: create new chunk failed:", cf_err)
 		os.exit(1)
 	}
 
-	chunk_stream := os.to_stream(chunk_file)
+	chunk_stream := os.to_stream(w.chunk_file)
 
 	return chunk_stream
 }
 
 @(private)
-open_asset :: proc(path: string) -> (io.Stream, u64) {
-	if asset_file != nil do os.close(asset_file) // close previous
+open_asset :: proc(w: ^Writer, path: string) -> (io.Stream, u64) {
+	if w.asset_file != nil do os.close(w.asset_file) // close previous
 
 	// Open asset
 	asset, open_err := os.open(path, {.Read})
diff --git a/src/file/write_metadata.odin b/src/file/write_metadata.odin
index 849b10b..22c49a9 100644
--- a/src/file/write_metadata.odin
+++ b/src/file/write_metadata.odin
@@ -8,6 +8,7 @@ import "core:os"
 // -----------------------------------------
 
 write_metadata :: proc(
+	w: ^Writer,
 	output: ^os.File,
 	entries: []FileEntry,
 	size_per_chunk: u64 = SIZE_PER_CHUNK,
@@ -28,20 +29,22 @@ write_metadata :: proc(
 	}
 	defer os.close(chunk_file)
 
-	write_header(chunk_file, number_of_assets, size_per_chunk, compression)
+	write_header(w, chunk_file, number_of_assets, size_per_chunk, compression)
 
-	write_asset_index(chunk_file, entries, number_of_assets, allocator)
+	write_asset_index(w, chunk_file, entries, number_of_assets, allocator)
 }
 
 @(private)
 write_header :: proc(
+	w: ^Writer,
 	chunk_file: ^os.File,
 	number_of_assets: u32,
 	size_per_chunk: u64 = SIZE_PER_CHUNK,
 	compression: u16 = COMPRESSION,
 ) {
-	last_offset := offsets.asset_offsets[len(offsets.asset_offsets) - 1]
-	last_size := offsets.asset_sizes[len(offsets.asset_sizes) - 1]
+	last_offset :=
+		w.asset_table.asset_offsets[len(w.asset_table.asset_offsets) - 1]
+	last_size := w.asset_table.asset_sizes[len(w.asset_table.asset_sizes) - 1]
 	total_size := last_offset + last_size
 
 	header := Header {
@@ -64,6 +67,7 @@ write_header :: proc(
 
 @(private)
 write_asset_index :: proc(
+	w: ^Writer,
 	chunk_file: ^os.File,
 	entries: []FileEntry,
 	number_of_assets: u32,
@@ -90,8 +94,8 @@ write_asset_index :: proc(
 
 		ai := cast(^AssetIndex)offset_pointer
 		copy(ai.relpath[:PATH_SIZE], f.relpath)
-		ai.size = offsets.asset_sizes[i]
-		ai.offset = offsets.asset_offsets[i]
+		ai.size = w.asset_table.asset_sizes[i]
+		ai.offset = w.asset_table.asset_offsets[i]
 	}
 
 	assert(len(index_bytes) % size_of(AssetIndex) == 0) // clean multiple
@@ -100,7 +104,7 @@ write_asset_index :: proc(
 	n, err := os.write_at(
 		chunk_file,
 		index_bytes,
-		cast(i64)offsets.asset_index_offset,
+		cast(i64)w.asset_table.asset_index_offset,
 	)
 	if err != nil {
 		fmt.eprintln("error: chunk write error:", err)
diff --git a/src/main.odin b/src/main.odin
index 5603f48..0e86cd1 100644
--- a/src/main.odin
+++ b/src/main.odin
@@ -20,8 +20,16 @@ main :: proc() {
 	entries := file.list_dir_recursive(opts.input)
 	defer file.delete_entries(&entries)
 
-	file.compute_metadata_offsets(cast(u64)len(entries))
-	file.write_assets(opts.output, entries[:], opts.size, opts.compression)
-	file.write_metadata(opts.output, entries[:], opts.size, opts.compression)
-	file.delete_offsets()
+	w := file.writer_init(cast(u64)len(entries))
+	defer file.writer_destroy(&w)
+
+	file.write_assets(&w, opts.output, entries[:], opts.size, opts.compression)
+
+	file.write_metadata(
+		&w,
+		opts.output,
+		entries[:],
+		opts.size,
+		opts.compression,
+	)
 }