diff --git a/lib/compiler/objcopy.zig b/lib/compiler/objcopy.zig
index 600166288c..77b60c9b37 100644
--- a/lib/compiler/objcopy.zig
+++ b/lib/compiler/objcopy.zig
@@ -25,11 +25,15 @@ pub fn main() !void {
     var general_purpose_allocator: std.heap.GeneralPurposeAllocator(.{}) = .init;
     const gpa = general_purpose_allocator.allocator();
 
+    var threaded: std.Io.Threaded = .init(gpa, .{});
+    defer threaded.deinit();
+    const io = threaded.io();
+
     const args = try std.process.argsAlloc(arena);
-    return cmdObjCopy(gpa, arena, args[1..]);
+    return cmdObjCopy(arena, io, args[1..]);
 }
 
-fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
+fn cmdObjCopy(arena: Allocator, io: Io, args: []const []const u8) !void {
     var i: usize = 0;
     var opt_out_fmt: ?std.Target.ObjectFormat = null;
     var opt_input: ?[]const u8 = null;
@@ -57,7 +61,7 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
                 fatal("unexpected positional argument: '{s}'", .{arg});
             }
         } else if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
-            return Io.File.stdout().writeAll(usage);
+            return Io.File.stdout().writeStreamingAll(io, usage);
         } else if (mem.eql(u8, arg, "-O") or mem.eql(u8, arg, "--output-target")) {
             i += 1;
             if (i >= args.len) fatal("expected another argument after '{s}'", .{arg});
@@ -148,11 +152,7 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
     const input = opt_input orelse fatal("expected input parameter", .{});
     const output = opt_output orelse fatal("expected output parameter", .{});
 
-    var threaded: std.Io.Threaded = .init(gpa, .{});
-    defer threaded.deinit();
-    const io = threaded.io();
-
-    const input_file = Io.Dir.cwd().openFile(input, .{}) catch |err| fatal("failed to open {s}: {t}", .{ input, err });
+    const input_file = Io.Dir.cwd().openFile(io, input, .{}) catch |err| fatal("failed to open {s}: {t}", .{ input, err });
     defer input_file.close(io);
 
     const stat = input_file.stat(io) catch |err| fatal("failed to stat {s}: {t}", .{ input, err });
@@ -178,9 +178,9 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
         }
     };
 
-    const mode = if (out_fmt != .elf or only_keep_debug) Io.File.default_mode else stat.mode;
+    const permissions: Io.File.Permissions = if (out_fmt != .elf or only_keep_debug) .default_file else stat.permissions;
 
-    var output_file = try Io.Dir.cwd().createFile(io, output, .{ .mode = mode });
+    var output_file = try Io.Dir.cwd().createFile(io, output, .{ .permissions = permissions });
     defer output_file.close(io);
 
     var out = output_file.writer(io, &output_buffer);
@@ -223,7 +223,7 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
 
     if (listen) {
         var stdin_reader = Io.File.stdin().reader(io, &stdin_buffer);
-        var stdout_writer = Io.File.stdout().writer(&stdout_buffer);
+        var stdout_writer = Io.File.stdout().writer(io, &stdout_buffer);
         var server = try Server.init(.{
             .in = &stdin_reader.interface,
             .out = &stdout_writer.interface,
diff --git a/tools/dump-cov.zig b/tools/dump-cov.zig
index d52b61f058..211fe25197 100644
--- a/tools/dump-cov.zig
+++ b/tools/dump-cov.zig
@@ -51,8 +51,8 @@ pub fn main() !void {
     var coverage: std.debug.Coverage = .init;
     defer coverage.deinit(gpa);
 
-    var debug_info = std.debug.Info.load(gpa, exe_path, &coverage, target.ofmt, target.cpu.arch) catch |err| {
-        fatal("failed to load debug info for {f}: {s}", .{ exe_path, @errorName(err) });
+    var debug_info = std.debug.Info.load(gpa, io, exe_path, &coverage, target.ofmt, target.cpu.arch) catch |err| {
+        fatal("failed to load debug info for {f}: {t}", .{ exe_path, err });
     };
     defer debug_info.deinit(gpa);
 
diff --git a/tools/gen_spirv_spec.zig b/tools/gen_spirv_spec.zig
index c211d1022e..072de6573e 100644
--- a/tools/gen_spirv_spec.zig
+++ b/tools/gen_spirv_spec.zig
@@ -930,8 +930,9 @@ fn parseHexInt(text: []const u8) !u31 {
 }
 
 fn usageAndExit(arg0: []const u8, code: u8) noreturn {
-    const stderr, _ = std.debug.lockStderrWriter(&.{});
-    stderr.print(
+    const stderr = std.debug.lockStderr(&.{});
+    const w = &stderr.file_writer.interface;
+    w.print(
         \\Usage: {s} <SPIRV-Headers repository path> <path/to/zig/src/codegen/spirv/extinst.zig.grammar.json>
         \\
         \\Generates Zig bindings for SPIR-V specifications found in the SPIRV-Headers
diff --git a/tools/generate_linux_syscalls.zig b/tools/generate_linux_syscalls.zig
index 789cb95116..ebdc7a6e2f 100644
--- a/tools/generate_linux_syscalls.zig
+++ b/tools/generate_linux_syscalls.zig
@@ -181,8 +181,8 @@ pub fn main() !void {
 
     const args = try std.process.argsAlloc(gpa);
     if (args.len < 2 or mem.eql(u8, args[1], "--help")) {
-        const w, _ = std.debug.lockStderrWriter(&.{});
-        defer std.debug.unlockStderrWriter();
+        const stderr = std.debug.lockStderr(&.{});
+        const w = &stderr.file_writer.interface;
         usage(w, args[0]) catch std.process.exit(2);
         std.process.exit(1);
     }
diff --git a/tools/update-linux-headers.zig b/tools/update-linux-headers.zig
index 2d71d8c718..c3614e5416 100644
--- a/tools/update-linux-headers.zig
+++ b/tools/update-linux-headers.zig
@@ -197,7 +197,7 @@ pub fn main() !void {
             try dir_stack.append(target_include_dir);
 
             while (dir_stack.pop()) |full_dir_name| {
-                var dir = Dir.cwd().openDir(full_dir_name, .{ .iterate = true }) catch |err| switch (err) {
+                var dir = Dir.cwd().openDir(io, full_dir_name, .{ .iterate = true }) catch |err| switch (err) {
                     error.FileNotFound => continue :search,
                     error.AccessDenied => continue :search,
                     else => return err,
@@ -213,7 +213,7 @@ pub fn main() !void {
                         .file => {
                             const rel_path = try Dir.path.relative(arena, target_include_dir, full_path);
                             const max_size = 2 * 1024 * 1024 * 1024;
-                            const raw_bytes = try Dir.cwd().readFileAlloc(full_path, arena, .limited(max_size));
+                            const raw_bytes = try Dir.cwd().readFileAlloc(io, full_path, arena, .limited(max_size));
                             const trimmed = std.mem.trim(u8, raw_bytes, " \r\n\t");
                             total_bytes += raw_bytes.len;
                             const hash = try arena.alloc(u8, 32);
diff --git a/tools/update_clang_options.zig b/tools/update_clang_options.zig
index c8b941cbfa..5f3c7f40b5 100644
--- a/tools/update_clang_options.zig
+++ b/tools/update_clang_options.zig
@@ -961,8 +961,8 @@ fn objectLessThan(context: void, a: *json.ObjectMap, b: *json.ObjectMap) bool {
 }
 
 fn printUsageAndExit(arg0: []const u8) noreturn {
-    const w, _ = std.debug.lockStderrWriter(&.{});
-    defer std.debug.unlockStderrWriter();
+    const stderr = std.debug.lockStderr(&.{});
+    const w = &stderr.file_writer.interface;
     printUsage(w, arg0) catch std.process.exit(2);
     std.process.exit(1);
 }
diff --git a/tools/update_cpu_features.zig b/tools/update_cpu_features.zig
index e49ca4d01a..95864c586a 100644
--- a/tools/update_cpu_features.zig
+++ b/tools/update_cpu_features.zig
@@ -2426,8 +2426,9 @@ fn processOneTarget(io: Io, job: Job) void {
 }
 
 fn usageAndExit(arg0: []const u8, code: u8) noreturn {
-    const stderr, _ = std.debug.lockStderrWriter(&.{});
-    stderr.print(
+    const stderr = std.debug.lockStderr(&.{});
+    const w = &stderr.file_writer.interface;
+    w.print(
         \\Usage: {s} /path/to/llvm-tblgen /path/git/llvm-project /path/git/zig [zig_name filter]
         \\
         \\Updates lib/std/target/<target>.zig from llvm/lib/Target/<Target>/<Target>.td .
diff --git a/tools/update_crc_catalog.zig b/tools/update_crc_catalog.zig
index 16ae58a564..f1448b1278 100644
--- a/tools/update_crc_catalog.zig
+++ b/tools/update_crc_catalog.zig
@@ -195,8 +195,8 @@ pub fn main() anyerror!void {
 }
 
 fn printUsageAndExit(arg0: []const u8) noreturn {
-    const w, _ = std.debug.lockStderrWriter(&.{});
-    defer std.debug.unlockStderrWriter();
+    const stderr = std.debug.lockStderr(&.{});
+    const w = &stderr.file_writer.interface;
     printUsage(w, arg0) catch std.process.exit(2);
     std.process.exit(1);
 }