diff --git a/lib/compiler/resinator/cvtres.zig b/lib/compiler/resinator/cvtres.zig
index 27e14ae9a3..e181b9390e 100644
--- a/lib/compiler/resinator/cvtres.zig
+++ b/lib/compiler/resinator/cvtres.zig
@@ -665,19 +665,16 @@ const ResourceTree = struct {
     pub fn writeCoff(
         self: *const ResourceTree,
         allocator: Allocator,
-        writer: anytype,
+        w: anytype,
         resources_in_data_order: []const Resource,
         lengths: Lengths,
         coff_string_table: *StringTable,
     ) ![]const std.coff.Symbol {
         if (self.type_to_name_map.count() == 0) {
-            try writer.writeByteNTimes(0, 16);
+            try w.writeByteNTimes(0, 16);
             return &.{};
         }
 
-        var counting_writer = std.io.countingWriter(writer);
-        const w = counting_writer.writer();
-
         var level2_list: std.ArrayListUnmanaged(*const NameToLanguageMap) = .empty;
         defer level2_list.deinit(allocator);
 
@@ -735,7 +732,6 @@ const ResourceTree = struct {
                 try level2_list.append(allocator, name_to_lang_map);
             }
         }
-        std.debug.assert(counting_writer.bytes_written == level2_start);
 
         const level3_start = level2_start + lengths.level2;
         var level3_address = level3_start;
@@ -771,7 +767,6 @@ const ResourceTree = struct {
                 try level3_list.append(allocator, lang_to_resources_map);
             }
         }
-        std.debug.assert(counting_writer.bytes_written == level3_start);
 
         var reloc_addresses = try allocator.alloc(u32, resources_in_data_order.len);
         defer allocator.free(reloc_addresses);
@@ -813,7 +808,6 @@ const ResourceTree = struct {
                 try resources_list.append(allocator, reloc_resource);
             }
         }
-        std.debug.assert(counting_writer.bytes_written == data_entries_start);
 
         for (resources_list.items, 0..) |reloc_resource, i| {
             // TODO: This logic works but is convoluted, would be good to clean this up
@@ -827,7 +821,6 @@ const ResourceTree = struct {
             };
             try w.writeStructEndian(data_entry, .little);
         }
-        std.debug.assert(counting_writer.bytes_written == strings_start);
 
         for (self.rsrc_string_table.keys()) |v| {
             const str = v.name;
diff --git a/lib/std/Io.zig b/lib/std/Io.zig
index 746a457c5b..3ad511242b 100644
--- a/lib/std/Io.zig
+++ b/lib/std/Io.zig
@@ -432,10 +432,6 @@ pub const FixedBufferStream = @import("Io/fixed_buffer_stream.zig").FixedBufferS
 /// Deprecated in favor of `Reader`.
 pub const fixedBufferStream = @import("Io/fixed_buffer_stream.zig").fixedBufferStream;
 /// Deprecated with no replacement; inefficient pattern
-pub const CountingWriter = @import("Io/counting_writer.zig").CountingWriter;
-/// Deprecated with no replacement; inefficient pattern
-pub const countingWriter = @import("Io/counting_writer.zig").countingWriter;
-/// Deprecated with no replacement; inefficient pattern
 pub const CountingReader = @import("Io/counting_reader.zig").CountingReader;
 /// Deprecated with no replacement; inefficient pattern
 pub const countingReader = @import("Io/counting_reader.zig").countingReader;
@@ -917,7 +913,6 @@ test {
     _ = Reader;
     _ = Writer;
     _ = BufferedWriter;
-    _ = CountingWriter;
     _ = CountingReader;
     _ = FixedBufferStream;
     _ = tty;
diff --git a/lib/std/Io/Writer.zig b/lib/std/Io/Writer.zig
index 797a69914c..dd3994c413 100644
--- a/lib/std/Io/Writer.zig
+++ b/lib/std/Io/Writer.zig
@@ -2239,6 +2239,11 @@ pub const Discarding = struct {
         };
     }
 
+    /// Includes buffered data (no need to flush).
+    pub fn fullCount(d: *const Discarding) u64 {
+        return d.count + d.writer.end;
+    }
+
     pub fn drain(w: *Writer, data: []const []const u8, splat: usize) Error!usize {
         const d: *Discarding = @alignCast(@fieldParentPtr("writer", w));
         const slice = data[0 .. data.len - 1];
diff --git a/lib/std/Io/counting_writer.zig b/lib/std/Io/counting_writer.zig
deleted file mode 100644
index 32c3ed930f..0000000000
--- a/lib/std/Io/counting_writer.zig
+++ /dev/null
@@ -1,39 +0,0 @@
-const std = @import("../std.zig");
-const io = std.io;
-const testing = std.testing;
-
-/// A Writer that counts how many bytes has been written to it.
-pub fn CountingWriter(comptime WriterType: type) type {
-    return struct {
-        bytes_written: u64,
-        child_stream: WriterType,
-
-        pub const Error = WriterType.Error;
-        pub const Writer = io.GenericWriter(*Self, Error, write);
-
-        const Self = @This();
-
-        pub fn write(self: *Self, bytes: []const u8) Error!usize {
-            const amt = try self.child_stream.write(bytes);
-            self.bytes_written += amt;
-            return amt;
-        }
-
-        pub fn writer(self: *Self) Writer {
-            return .{ .context = self };
-        }
-    };
-}
-
-pub fn countingWriter(child_stream: anytype) CountingWriter(@TypeOf(child_stream)) {
-    return .{ .bytes_written = 0, .child_stream = child_stream };
-}
-
-test CountingWriter {
-    var counting_stream = countingWriter(std.io.null_writer);
-    const stream = counting_stream.writer();
-
-    const bytes = "yay" ** 100;
-    stream.writeAll(bytes) catch unreachable;
-    try testing.expect(counting_stream.bytes_written == bytes.len);
-}
diff --git a/lib/std/crypto/phc_encoding.zig b/lib/std/crypto/phc_encoding.zig
index 507a02b983..e53977b42b 100644
--- a/lib/std/crypto/phc_encoding.zig
+++ b/lib/std/crypto/phc_encoding.zig
@@ -5,6 +5,7 @@ const fmt = std.fmt;
 const io = std.io;
 const mem = std.mem;
 const meta = std.meta;
+const Writer = std.Io.Writer;
 
 const fields_delimiter = "$";
 const fields_delimiter_scalar = '$';
@@ -188,19 +189,20 @@ pub fn deserialize(comptime HashResult: type, str: []const u8) Error!HashResult
 ///
 /// `params` can also include any additional parameters.
 pub fn serialize(params: anytype, str: []u8) Error![]const u8 {
-    var buf = io.fixedBufferStream(str);
-    try serializeTo(params, buf.writer());
-    return buf.getWritten();
+    var w: Writer = .fixed(str);
+    serializeTo(params, &w) catch return error.NoSpaceLeft;
+    return w.buffered();
 }
 
 /// Compute the number of bytes required to serialize `params`
 pub fn calcSize(params: anytype) usize {
-    var buf = io.countingWriter(io.null_writer);
-    serializeTo(params, buf.writer()) catch unreachable;
-    return @as(usize, @intCast(buf.bytes_written));
+    var trash: [128]u8 = undefined;
+    var d: Writer.Discarding = .init(&trash);
+    serializeTo(params, &d.writer) catch unreachable;
+    return @intCast(d.fullCount());
 }
 
-fn serializeTo(params: anytype, out: anytype) !void {
+fn serializeTo(params: anytype, out: *std.Io.Writer) !void {
     const HashResult = @TypeOf(params);
 
     if (@hasField(HashResult, version_param_name)) {
diff --git a/lib/std/crypto/scrypt.zig b/lib/std/crypto/scrypt.zig
index 23202e7937..f12306a1dc 100644
--- a/lib/std/crypto/scrypt.zig
+++ b/lib/std/crypto/scrypt.zig
@@ -311,9 +311,10 @@ const crypt_format = struct {
 
     /// Compute the number of bytes required to serialize `params`
     pub fn calcSize(params: anytype) usize {
-        var buf = io.countingWriter(io.null_writer);
-        serializeTo(params, buf.writer()) catch unreachable;
-        return @as(usize, @intCast(buf.bytes_written));
+        var trash: [128]u8 = undefined;
+        var d: std.Io.Writer.Discarding = .init(&trash);
+        serializeTo(params, &d) catch unreachable;
+        return @intCast(d.fullCount());
     }
 
     fn serializeTo(params: anytype, out: anytype) !void {
diff --git a/src/arch/x86_64/encoder.zig b/src/arch/x86_64/encoder.zig
index 43d23af5fc..ed31c068dc 100644
--- a/src/arch/x86_64/encoder.zig
+++ b/src/arch/x86_64/encoder.zig
@@ -1204,11 +1204,10 @@ const TestEncode = struct {
         mnemonic: Instruction.Mnemonic,
         ops: []const Instruction.Operand,
     ) !void {
-        var stream = std.io.fixedBufferStream(&enc.buffer);
-        var count_writer = std.io.countingWriter(stream.writer());
+        var writer: std.Io.Writer = .fixed(&enc.buffer);
         const inst: Instruction = try .new(.none, mnemonic, ops);
-        try inst.encode(count_writer.writer(), .{});
-        enc.index = count_writer.bytes_written;
+        try inst.encode(&writer, .{});
+        enc.index = writer.bufferedLen();
     }
 
     fn code(enc: TestEncode) []const u8 {
diff --git a/src/link/Dwarf.zig b/src/link/Dwarf.zig
index f11ebc94d4..5c805e6a7e 100644
--- a/src/link/Dwarf.zig
+++ b/src/link/Dwarf.zig
@@ -1,4 +1,4 @@
-gpa: std.mem.Allocator,
+gpa: Allocator,
 bin_file: *link.File,
 format: DW.Format,
 endian: std.builtin.Endian,
@@ -21,6 +21,7 @@ debug_rnglists: DebugRngLists,
 debug_str: StringSection,
 
 pub const UpdateError = error{
+    WriteFailed,
     ReinterpretDeclRef,
     Unimplemented,
     EndOfStream,
@@ -50,7 +51,7 @@ const ModInfo = struct {
     dirs: std.AutoArrayHashMapUnmanaged(Unit.Index, void),
     files: std.AutoArrayHashMapUnmanaged(Zcu.File.Index, void),
 
-    fn deinit(mod_info: *ModInfo, gpa: std.mem.Allocator) void {
+    fn deinit(mod_info: *ModInfo, gpa: Allocator) void {
         mod_info.dirs.deinit(gpa);
         mod_info.files.deinit(gpa);
         mod_info.* = undefined;
@@ -220,7 +221,7 @@ const StringSection = struct {
         .section = Section.init,
     };
 
-    fn deinit(str_sec: *StringSection, gpa: std.mem.Allocator) void {
+    fn deinit(str_sec: *StringSection, gpa: Allocator) void {
         str_sec.contents.deinit(gpa);
         str_sec.map.deinit(gpa);
         str_sec.section.deinit(gpa);
@@ -297,7 +298,7 @@ pub const Section = struct {
         .len = 0,
     };
 
-    fn deinit(sec: *Section, gpa: std.mem.Allocator) void {
+    fn deinit(sec: *Section, gpa: Allocator) void {
         for (sec.units.items) |*unit| unit.deinit(gpa);
         sec.units.deinit(gpa);
         sec.* = undefined;
@@ -357,7 +358,7 @@ pub const Section = struct {
         if (sec.last == unit.toOptional()) sec.last = unit_ptr.prev;
     }
 
-    fn popUnit(sec: *Section, gpa: std.mem.Allocator) void {
+    fn popUnit(sec: *Section, gpa: Allocator) void {
         const unit_index: Unit.Index = @enumFromInt(sec.units.items.len - 1);
         sec.unlinkUnit(unit_index);
         var unit = sec.units.pop().?;
@@ -518,7 +519,7 @@ const Unit = struct {
         unit.cross_section_relocs.clearRetainingCapacity();
     }
 
-    fn deinit(unit: *Unit, gpa: std.mem.Allocator) void {
+    fn deinit(unit: *Unit, gpa: Allocator) void {
         for (unit.entries.items) |*entry| entry.deinit(gpa);
         unit.entries.deinit(gpa);
         unit.cross_unit_relocs.deinit(gpa);
@@ -526,7 +527,7 @@ const Unit = struct {
         unit.* = undefined;
     }
 
-    fn addEntry(unit: *Unit, gpa: std.mem.Allocator) std.mem.Allocator.Error!Entry.Index {
+    fn addEntry(unit: *Unit, gpa: Allocator) Allocator.Error!Entry.Index {
         if (unit.free.unwrap()) |entry| {
             const entry_ptr = unit.getEntry(entry);
             unit.free = entry_ptr.next;
@@ -780,7 +781,7 @@ const Entry = struct {
         entry.external_relocs.clearRetainingCapacity();
     }
 
-    fn deinit(entry: *Entry, gpa: std.mem.Allocator) void {
+    fn deinit(entry: *Entry, gpa: Allocator) void {
         entry.cross_entry_relocs.deinit(gpa);
         entry.cross_unit_relocs.deinit(gpa);
         entry.cross_section_relocs.deinit(gpa);
@@ -1133,7 +1134,7 @@ pub const Loc = union(enum) {
         };
     }
 
-    fn writeReg(reg: u32, op0: u8, opx: u8, writer: anytype) @TypeOf(writer).Error!void {
+    fn writeReg(reg: u32, op0: u8, opx: u8, writer: anytype) !void {
         if (std.math.cast(u5, reg)) |small_reg| {
             try writer.writeByte(op0 + small_reg);
         } else {
@@ -1142,7 +1143,7 @@ pub const Loc = union(enum) {
         }
     }
 
-    fn write(loc: Loc, adapter: anytype) UpdateError!void {
+    fn write(loc: Loc, adapter: anytype) !void {
         const writer = adapter.writer();
         switch (loc) {
             .empty => {},
@@ -1712,15 +1713,15 @@ pub const WipNav = struct {
         wip_nav.func = func;
     }
 
-    fn externalReloc(wip_nav: *WipNav, sec: *Section, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+    fn externalReloc(wip_nav: *WipNav, sec: *Section, reloc: ExternalReloc) Allocator.Error!void {
         try sec.getUnit(wip_nav.unit).getEntry(wip_nav.entry).external_relocs.append(wip_nav.dwarf.gpa, reloc);
     }
 
-    pub fn infoExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+    pub fn infoExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) Allocator.Error!void {
         try wip_nav.externalReloc(&wip_nav.dwarf.debug_info.section, reloc);
     }
 
-    fn frameExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) std.mem.Allocator.Error!void {
+    fn frameExternalReloc(wip_nav: *WipNav, reloc: ExternalReloc) Allocator.Error!void {
         try wip_nav.externalReloc(&wip_nav.dwarf.debug_frame.section, reloc);
     }
 
@@ -1768,33 +1769,33 @@ pub const WipNav = struct {
     }
 
     const ExprLocCounter = struct {
-        const Stream = std.io.CountingWriter(std.io.NullWriter);
-        stream: Stream,
+        stream: Writer.Discarding,
         section_offset_bytes: u32,
         address_size: AddressSize,
-        fn init(dwarf: *Dwarf) ExprLocCounter {
+        fn init(dwarf: *Dwarf, trash_buffer: []u8) ExprLocCounter {
             return .{
-                .stream = std.io.countingWriter(std.io.null_writer),
+                .stream = .init(trash_buffer),
                 .section_offset_bytes = dwarf.sectionOffsetBytes(),
                 .address_size = dwarf.address_size,
             };
         }
-        fn writer(counter: *ExprLocCounter) Stream.Writer {
-            return counter.stream.writer();
+        fn writer(counter: *ExprLocCounter) *Writer {
+            return &counter.stream.writer;
         }
         fn endian(_: ExprLocCounter) std.builtin.Endian {
             return @import("builtin").cpu.arch.endian();
         }
         fn addrSym(counter: *ExprLocCounter, _: u32) error{}!void {
-            counter.stream.bytes_written += @intFromEnum(counter.address_size);
+            counter.stream.count += @intFromEnum(counter.address_size);
         }
         fn infoEntry(counter: *ExprLocCounter, _: Unit.Index, _: Entry.Index) error{}!void {
-            counter.stream.bytes_written += counter.section_offset_bytes;
+            counter.stream.count += counter.section_offset_bytes;
         }
     };
 
     fn infoExprLoc(wip_nav: *WipNav, loc: Loc) UpdateError!void {
-        var counter: ExprLocCounter = .init(wip_nav.dwarf);
+        var trash_buffer: [64]u8 = undefined;
+        var counter: ExprLocCounter = .init(wip_nav.dwarf, &trash_buffer);
         try loc.write(&counter);
 
         const adapter: struct {
@@ -1812,7 +1813,7 @@ pub const WipNav = struct {
                 try ctx.wip_nav.infoSectionOffset(.debug_info, unit, entry, 0);
             }
         } = .{ .wip_nav = wip_nav };
-        try uleb128(adapter.writer(), counter.stream.bytes_written);
+        try uleb128(adapter.writer(), counter.stream.fullCount());
         try loc.write(adapter);
     }
 
@@ -1826,7 +1827,8 @@ pub const WipNav = struct {
     }
 
     fn frameExprLoc(wip_nav: *WipNav, loc: Loc) UpdateError!void {
-        var counter: ExprLocCounter = .init(wip_nav.dwarf);
+        var trash_buffer: [64]u8 = undefined;
+        var counter: ExprLocCounter = .init(wip_nav.dwarf, &trash_buffer);
         try loc.write(&counter);
 
         const adapter: struct {
@@ -1844,7 +1846,7 @@ pub const WipNav = struct {
                 try ctx.wip_nav.sectionOffset(.debug_frame, .debug_info, unit, entry, 0);
             }
         } = .{ .wip_nav = wip_nav };
-        try uleb128(adapter.writer(), counter.stream.bytes_written);
+        try uleb128(adapter.writer(), counter.stream.fullCount());
         try loc.write(adapter);
     }
 
@@ -1922,7 +1924,7 @@ pub const WipNav = struct {
         try wip_nav.infoSectionOffset(.debug_info, unit, entry, 0);
     }
 
-    fn refForward(wip_nav: *WipNav) std.mem.Allocator.Error!u32 {
+    fn refForward(wip_nav: *WipNav) Allocator.Error!u32 {
         const dwarf = wip_nav.dwarf;
         const cross_entry_relocs = &dwarf.debug_info.section.getUnit(wip_nav.unit).getEntry(wip_nav.entry).cross_entry_relocs;
         const reloc_index: u32 = @intCast(cross_entry_relocs.items.len);
@@ -6022,14 +6024,14 @@ fn sectionOffsetBytes(dwarf: *Dwarf) u32 {
 
 fn uleb128Bytes(value: anytype) u32 {
     var trash_buffer: [64]u8 = undefined;
-    var d: std.Io.Writer.Discarding = .init(&trash_buffer);
+    var d: Writer.Discarding = .init(&trash_buffer);
     d.writer.writeUleb128(value) catch unreachable;
     return @intCast(d.count + d.writer.end);
 }
 
 fn sleb128Bytes(value: anytype) u32 {
     var trash_buffer: [64]u8 = undefined;
-    var d: std.Io.Writer.Discarding = .init(&trash_buffer);
+    var d: Writer.Discarding = .init(&trash_buffer);
     d.writer.writeSleb128(value) catch unreachable;
     return @intCast(d.count + d.writer.end);
 }
@@ -6057,3 +6059,5 @@ const sleb128 = std.leb.writeIleb128;
 const std = @import("std");
 const target_info = @import("../target.zig");
 const uleb128 = std.leb.writeUleb128;
+const Allocator = std.mem.Allocator;
+const Writer = std.Io.Writer;
diff --git a/src/link/Elf.zig b/src/link/Elf.zig
index 785f200928..be6c050e5e 100644
--- a/src/link/Elf.zig
+++ b/src/link/Elf.zig
@@ -3152,10 +3152,11 @@ fn writeSyntheticSections(self: *Elf) !void {
 
     if (self.section_indexes.gnu_hash) |shndx| {
         const shdr = slice.items(.shdr)[shndx];
-        var buffer = try std.ArrayList(u8).initCapacity(gpa, self.gnu_hash.size());
-        defer buffer.deinit();
-        try self.gnu_hash.write(self, buffer.writer());
-        try self.pwriteAll(buffer.items, shdr.sh_offset);
+        var aw: std.Io.Writer.Allocating = .init(gpa);
+        try aw.ensureUnusedCapacity(self.gnu_hash.size());
+        defer aw.deinit();
+        try self.gnu_hash.write(self, &aw.writer);
+        try self.pwriteAll(aw.getWritten(), shdr.sh_offset);
     }
 
     if (self.section_indexes.versym) |shndx| {
diff --git a/src/link/Elf/synthetic_sections.zig b/src/link/Elf/synthetic_sections.zig
index 2ab71d8c49..efad44f68b 100644
--- a/src/link/Elf/synthetic_sections.zig
+++ b/src/link/Elf/synthetic_sections.zig
@@ -1237,17 +1237,14 @@ pub const GnuHashSection = struct {
         return header_size + hash.num_bloom * 8 + hash.num_buckets * 4 + hash.num_exports * 4;
     }
 
-    pub fn write(hash: GnuHashSection, elf_file: *Elf, writer: anytype) !void {
+    pub fn write(hash: GnuHashSection, elf_file: *Elf, writer: *std.Io.Writer) !void {
         const exports = getExports(elf_file);
         const export_off = elf_file.dynsym.count() - hash.num_exports;
 
-        var counting = std.io.countingWriter(writer);
-        const cwriter = counting.writer();
-
-        try cwriter.writeInt(u32, hash.num_buckets, .little);
-        try cwriter.writeInt(u32, export_off, .little);
-        try cwriter.writeInt(u32, hash.num_bloom, .little);
-        try cwriter.writeInt(u32, bloom_shift, .little);
+        try writer.writeInt(u32, hash.num_buckets, .little);
+        try writer.writeInt(u32, export_off, .little);
+        try writer.writeInt(u32, hash.num_bloom, .little);
+        try writer.writeInt(u32, bloom_shift, .little);
 
         const comp = elf_file.base.comp;
         const gpa = comp.gpa;
@@ -1271,7 +1268,7 @@ pub const GnuHashSection = struct {
             bloom[idx] |= @as(u64, 1) << @as(u6, @intCast((h >> bloom_shift) % 64));
         }
 
-        try cwriter.writeAll(mem.sliceAsBytes(bloom));
+        try writer.writeAll(mem.sliceAsBytes(bloom));
 
         // Fill in the hash bucket indices
         const buckets = try gpa.alloc(u32, hash.num_buckets);
@@ -1284,7 +1281,7 @@ pub const GnuHashSection = struct {
             }
         }
 
-        try cwriter.writeAll(mem.sliceAsBytes(buckets));
+        try writer.writeAll(mem.sliceAsBytes(buckets));
 
         // Finally, write the hash table
         const table = try gpa.alloc(u32, hash.num_exports);
@@ -1300,9 +1297,7 @@ pub const GnuHashSection = struct {
             }
         }
 
-        try cwriter.writeAll(mem.sliceAsBytes(table));
-
-        assert(counting.bytes_written == hash.size());
+        try writer.writeAll(mem.sliceAsBytes(table));
     }
 
     pub fn hasher(name: [:0]const u8) u32 {
diff --git a/src/link/MachO/dyld_info/Trie.zig b/src/link/MachO/dyld_info/Trie.zig
index ce56101e54..d96f2a54c8 100644
--- a/src/link/MachO/dyld_info/Trie.zig
+++ b/src/link/MachO/dyld_info/Trie.zig
@@ -186,17 +186,18 @@ const FinalizeNodeResult = struct {
 
 /// Updates offset of this node in the output byte stream.
 fn finalizeNode(self: *Trie, node_index: Node.Index, offset_in_trie: u32) !FinalizeNodeResult {
-    var stream = std.io.countingWriter(std.io.null_writer);
-    const writer = stream.writer();
+    var trash_buffer: [64]u8 = undefined;
+    var stream: std.Io.Writer.Discarding = .init(&trash_buffer);
+    const writer = &stream.writer;
     const slice = self.nodes.slice();
 
     var node_size: u32 = 0;
     if (slice.items(.is_terminal)[node_index]) {
         const export_flags = slice.items(.export_flags)[node_index];
         const vmaddr_offset = slice.items(.vmaddr_offset)[node_index];
-        try leb.writeUleb128(writer, export_flags);
-        try leb.writeUleb128(writer, vmaddr_offset);
-        try leb.writeUleb128(writer, stream.bytes_written);
+        try writer.writeUleb128(export_flags);
+        try writer.writeUleb128(vmaddr_offset);
+        try writer.writeUleb128(stream.fullCount());
     } else {
         node_size += 1; // 0x0 for non-terminal nodes
     }
@@ -206,13 +207,13 @@ fn finalizeNode(self: *Trie, node_index: Node.Index, offset_in_trie: u32) !Final
         const edge = &self.edges.items[edge_index];
         const next_node_offset = slice.items(.trie_offset)[edge.node];
         node_size += @intCast(edge.label.len + 1);
-        try leb.writeUleb128(writer, next_node_offset);
+        try writer.writeUleb128(next_node_offset);
     }
 
     const trie_offset = slice.items(.trie_offset)[node_index];
     const updated = offset_in_trie != trie_offset;
     slice.items(.trie_offset)[node_index] = offset_in_trie;
-    node_size += @intCast(stream.bytes_written);
+    node_size += @intCast(stream.fullCount());
 
     return .{ .node_size = node_size, .updated = updated };
 }