diff --git a/lib/compiler/libc.zig b/lib/compiler/libc.zig
index 7a6edf0c44dec4f5a6d2a3e324dfc6c9c11d8b2b..1aa9a587ae32d35405a85dbd627ce6b4ebb18205 100644
--- a/lib/compiler/libc.zig
+++ b/lib/compiler/libc.zig
@@ -50,7 +50,7 @@ pub fn main() !void {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try stdout.writeAll(usage_libc);
                     try stdout.flush();
-                    return std.process.cleanExit();
+                    return std.process.cleanExit(io);
                 } else if (mem.eql(u8, arg, "-target")) {
                     if (i + 1 >= args.len) fatal("expected parameter after {s}", .{arg});
                     i += 1;
@@ -110,7 +110,7 @@ pub fn main() !void {
             try stdout.writeByte('\n');
         }
         try stdout.flush();
-        return std.process.cleanExit();
+        return std.process.cleanExit(io);
     }
 
     if (input_file) |libc_file| {
diff --git a/lib/compiler/objcopy.zig b/lib/compiler/objcopy.zig
index 90fd122294ea7d5c935b8b48e651271376dd1662..2e272b074b83b8fc5c2cacf399303b82d72b325d 100644
--- a/lib/compiler/objcopy.zig
+++ b/lib/compiler/objcopy.zig
@@ -235,7 +235,7 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
             const hdr = try server.receiveMessage();
             switch (hdr.tag) {
                 .exit => {
-                    return std.process.cleanExit();
+                    return std.process.cleanExit(io);
                 },
                 .update => {
                     if (seen_update) fatal("zig objcopy only supports 1 update for now", .{});
@@ -250,7 +250,7 @@ fn cmdObjCopy(gpa: Allocator, arena: Allocator, args: []const []const u8) !void
             }
         }
     }
-    return std.process.cleanExit();
+    return std.process.cleanExit(io);
 }
 
 const usage =
diff --git a/lib/compiler/reduce.zig b/lib/compiler/reduce.zig
index 0c61111d10297b12555f78662a431ead685a9a8d..a93db3a6d7a20ac1e5d491c8dfd494c151ce8567 100644
--- a/lib/compiler/reduce.zig
+++ b/lib/compiler/reduce.zig
@@ -75,7 +75,7 @@ pub fn main() !void {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     const stdout = Io.File.stdout();
                     try stdout.writeAll(usage);
-                    return std.process.cleanExit();
+                    return std.process.cleanExit(io);
                 } else if (mem.eql(u8, arg, "--")) {
                     argv = args[i + 1 ..];
                     break;
@@ -278,10 +278,10 @@ pub fn main() !void {
         try tree.render(gpa, &rendered.writer, fixups);
         try Io.Dir.cwd().writeFile(io, .{ .sub_path = root_source_file_path, .data = rendered.written() });
 
-        return std.process.cleanExit();
+        return std.process.cleanExit(io);
     }
     std.debug.print("no more transformations found\n", .{});
-    return std.process.cleanExit();
+    return std.process.cleanExit(io);
 }
 
 fn sortTransformations(transformations: []Walk.Transformation, rng: std.Random) void {
diff --git a/src/fmt.zig b/src/fmt.zig
index bec3496e683507387e4a84f97827b43f8be66dec..55a68d1dc8b5467d7fbcfdad0908703dbd278284 100644
--- a/src/fmt.zig
+++ b/src/fmt.zig
@@ -60,7 +60,7 @@ pub fn run(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8) !
             if (mem.startsWith(u8, arg, "-")) {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try Io.File.stdout().writeStreamingAll(io, usage_fmt);
-                    return process.cleanExit();
+                    return process.cleanExit(io);
                 } else if (mem.eql(u8, arg, "--color")) {
                     if (i + 1 >= args.len) {
                         fatal("expected [auto|on|off] after --color", .{});
diff --git a/src/main.zig b/src/main.zig
index 160b9919eb3af68c0acb6df60e551d97f91b5d2f..115c1b521271d62009e9e413539c4feb4dd444e3 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -1038,7 +1038,7 @@ fn buildOutputType(
                 } else if (mem.startsWith(u8, arg, "-")) {
                     if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                         try Io.File.stdout().writeStreamingAll(io, usage_build_generic);
-                        return cleanExit();
+                        return cleanExit(io);
                     } else if (mem.eql(u8, arg, "--")) {
                         if (arg_mode == .run) {
                             // args_iter.i is 1, referring the next arg after "--" in ["--", ...]
@@ -3646,7 +3646,7 @@ fn buildOutputType(
                 all_args,
                 runtime_args_start,
             );
-            return cleanExit();
+            return cleanExit(io);
         },
         .ip4 => |ip4_addr| {
             const addr: Io.net.IpAddress = .{ .ip4 = ip4_addr };
@@ -3672,7 +3672,7 @@ fn buildOutputType(
                 all_args,
                 runtime_args_start,
             );
-            return cleanExit();
+            return cleanExit(io);
         },
     }
 
@@ -3755,7 +3755,7 @@ fn buildOutputType(
     }
 
     // Skip resource deallocation in release builds; let the OS do it.
-    return cleanExit();
+    return cleanExit(io);
 }
 
 const CreateModule = struct {
@@ -4176,7 +4176,7 @@ fn serve(
         defer if (comp.debugIncremental()) ids.mutex.unlock(io);
 
         switch (hdr.tag) {
-            .exit => return cleanExit(),
+            .exit => return cleanExit(io),
             .update => {
                 tracy.frameMark();
                 file_system_inputs.clearRetainingCapacity();
@@ -4462,7 +4462,7 @@ fn runOrTest(
                 switch (term) {
                     .Exited => |code| {
                         if (code == 0) {
-                            return cleanExit();
+                            return cleanExit(io);
                         } else {
                             process.exit(code);
                         }
@@ -4476,7 +4476,7 @@ fn runOrTest(
                 switch (term) {
                     .Exited => |code| {
                         if (code == 0) {
-                            return cleanExit();
+                            return cleanExit(io);
                         } else {
                             const cmd = try std.mem.join(arena, " ", argv.items);
                             fatal("the following test command failed with exit code {d}:\n{s}", .{ code, cmd });
@@ -4688,7 +4688,7 @@ fn cmdTranslateC(
         var file_reader = zig_file.reader(io, &.{});
         _ = try stdout_writer.interface.sendFileAll(&file_reader, .unlimited);
         try stdout_writer.interface.flush();
-        return cleanExit();
+        return cleanExit(io);
     }
 }
 
@@ -4735,7 +4735,7 @@ fn cmdInit(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8) !
                     template = .minimal;
                 } else if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try Io.File.stdout().writeStreamingAll(io, usage_init);
-                    return cleanExit();
+                    return cleanExit(io);
                 } else {
                     fatal("unrecognized parameter: '{s}'", .{arg});
                 }
@@ -4780,7 +4780,7 @@ fn cmdInit(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8) !
             if (ok_count == template_paths.len) {
                 std.log.info("see `zig build --help` for a menu of options", .{});
             }
-            return cleanExit();
+            return cleanExit(io);
         },
         .minimal => {
             writeSimpleTemplateFile(io, Package.Manifest.basename,
@@ -4813,11 +4813,11 @@ fn cmdInit(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8) !
                 // their `build.zig.zon` *after* writing their `build.zig`. So this one isn't fatal.
                 error.PathAlreadyExists => {
                     std.log.info("successfully populated '{s}', preserving existing '{s}'", .{ Package.Manifest.basename, Package.build_zig_basename });
-                    return cleanExit();
+                    return cleanExit(io);
                 },
             };
             std.log.info("successfully populated '{s}' and '{s}'", .{ Package.Manifest.basename, Package.build_zig_basename });
-            return cleanExit();
+            return cleanExit(io);
         },
     }
 }
@@ -5284,7 +5284,7 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8)
                     process.exit(1);
                 }
 
-                if (fetch_only) return cleanExit();
+                if (fetch_only) return cleanExit(io);
 
                 var source_buf = std.array_list.Managed(u8).init(gpa);
                 defer source_buf.deinit();
@@ -5420,7 +5420,7 @@ fn cmdBuild(gpa: Allocator, arena: Allocator, io: Io, args: []const []const u8)
 
             switch (term) {
                 .Exited => |code| {
-                    if (code == 0) return cleanExit();
+                    if (code == 0) return cleanExit(io);
                     // Indicates that the build runner has reported compile errors
                     // and this parent process does not need to report any further
                     // diagnostics.
@@ -5691,7 +5691,7 @@ fn jitCmd(
         .Exited => |code| {
             if (code == 0) {
                 if (options.capture != null) return;
-                return cleanExit();
+                return cleanExit(io);
             }
             const cmd = try std.mem.join(arena, " ", child_argv.items);
             fatal("the following build command failed with exit code {d}:\n{s}", .{ code, cmd });
@@ -6151,7 +6151,7 @@ fn cmdAstCheck(arena: Allocator, io: Io, args: []const []const u8) !void {
         if (mem.startsWith(u8, arg, "-")) {
             if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                 try Io.File.stdout().writeStreamingAll(io, usage_ast_check);
-                return cleanExit();
+                return cleanExit(io);
             } else if (mem.eql(u8, arg, "-t")) {
                 want_output_text = true;
             } else if (mem.eql(u8, arg, "--zon")) {
@@ -6222,7 +6222,7 @@ fn cmdAstCheck(arena: Allocator, io: Io, args: []const []const u8) !void {
                 if (zir.hasCompileErrors()) {
                     process.exit(1);
                 } else {
-                    return cleanExit();
+                    return cleanExit(io);
                 }
             }
             if (!build_options.enable_debug_extensions) {
@@ -6273,7 +6273,7 @@ fn cmdAstCheck(arena: Allocator, io: Io, args: []const []const u8) !void {
             if (zir.hasCompileErrors()) {
                 process.exit(1);
             } else {
-                return cleanExit();
+                return cleanExit(io);
             }
         },
         .zon => {
@@ -6288,7 +6288,7 @@ fn cmdAstCheck(arena: Allocator, io: Io, args: []const []const u8) !void {
             }
 
             if (!want_output_text) {
-                return cleanExit();
+                return cleanExit(io);
             }
 
             if (!build_options.enable_debug_extensions) {
@@ -6297,7 +6297,7 @@ fn cmdAstCheck(arena: Allocator, io: Io, args: []const []const u8) !void {
 
             try @import("print_zoir.zig").renderToWriter(zoir, arena, stdout_bw);
             try stdout_bw.flush();
-            return cleanExit();
+            return cleanExit(io);
         },
     }
 }
@@ -6325,7 +6325,7 @@ fn cmdDetectCpu(io: Io, args: []const []const u8) !void {
             if (mem.startsWith(u8, arg, "-")) {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try Io.File.stdout().writeStreamingAll(io, detect_cpu_usage);
-                    return cleanExit();
+                    return cleanExit(io);
                 } else if (mem.eql(u8, arg, "--llvm")) {
                     use_llvm = true;
                 } else {
@@ -6475,7 +6475,7 @@ fn cmdDumpLlvmInts(
     }
     try stdout_bw.flush();
 
-    return cleanExit();
+    return cleanExit(io);
 }
 
 /// This is only enabled for debug builds.
@@ -6909,7 +6909,7 @@ fn cmdFetch(
             if (mem.startsWith(u8, arg, "-")) {
                 if (mem.eql(u8, arg, "-h") or mem.eql(u8, arg, "--help")) {
                     try Io.File.stdout().writeStreamingAll(io, usage_fetch);
-                    return cleanExit();
+                    return cleanExit(io);
                 } else if (mem.eql(u8, arg, "--global-cache-dir")) {
                     if (i + 1 >= args.len) fatal("expected argument after '{s}'", .{arg});
                     i += 1;
@@ -7020,7 +7020,7 @@ fn cmdFetch(
             var stdout = Io.File.stdout().writerStreaming(io, &stdout_buffer);
             try stdout.interface.print("{s}\n", .{package_hash_slice});
             try stdout.interface.flush();
-            return cleanExit();
+            return cleanExit(io);
         },
         .yes, .exact => |name| name: {
             if (name) |n| break :name n;
@@ -7159,7 +7159,7 @@ fn cmdFetch(
         fatal("unable to write {s} file: {t}", .{ Package.Manifest.basename, err });
     };
 
-    return cleanExit();
+    return cleanExit(io);
 }
 
 fn createEmptyDependenciesModule(