diff --git a/cmake/targets/BuildLibuv.cmake b/cmake/targets/BuildLibuv.cmake
index af49601f33..76814059fa 100644
--- a/cmake/targets/BuildLibuv.cmake
+++ b/cmake/targets/BuildLibuv.cmake
@@ -4,7 +4,7 @@ register_repository(
   REPOSITORY
     oven-sh/libuv
   COMMIT
-    537d74411e9a5587bc5c6dd9ca04a77976ecb120
+    271d173b6ebd4dfeb692862df2b03af48dcfb16b
 )
 
 if(WIN32)
diff --git a/repro-hell/beancounter.ts b/repro-hell/beancounter.ts
new file mode 100644
index 0000000000..cb917e504c
--- /dev/null
+++ b/repro-hell/beancounter.ts
@@ -0,0 +1,7 @@
+let count = 0;
+process.stdin.on("data", chunk => {
+  count += chunk.length;
+});
+process.stdin.on("end", () => {
+  console.log(count);
+});
diff --git a/repro-hell/reader.ts b/repro-hell/reader.ts
new file mode 100644
index 0000000000..bd57a04987
--- /dev/null
+++ b/repro-hell/reader.ts
@@ -0,0 +1 @@
+process.stdin.pipe(process.stdout);
diff --git a/src/bun.js/api/bun/subprocess/StaticPipeWriter.zig b/src/bun.js/api/bun/subprocess/StaticPipeWriter.zig
index 4679de7699..91c9213821 100644
--- a/src/bun.js/api/bun/subprocess/StaticPipeWriter.zig
+++ b/src/bun.js/api/bun/subprocess/StaticPipeWriter.zig
@@ -1,3 +1,5 @@
+const mlog = @import("../../../../mlog.zig").log;
+
 pub fn NewStaticPipeWriter(comptime ProcessType: type) type {
     return struct {
         const This = @This();
@@ -35,6 +37,7 @@ pub fn NewStaticPipeWriter(comptime ProcessType: type) type {
         }
 
         pub fn close(this: *This) void {
+            mlog("StaticPipeWriter(0x{x}) close()\n", .{@intFromPtr(this)});
             log("StaticPipeWriter(0x{x}) close()", .{@intFromPtr(this)});
             this.writer.close();
         }
@@ -60,6 +63,7 @@ pub fn NewStaticPipeWriter(comptime ProcessType: type) type {
         }
 
         pub fn start(this: *This) bun.sys.Maybe(void) {
+            mlog("StaticPipeWriter(0x{x}) start()\n", .{@intFromPtr(this)});
             log("StaticPipeWriter(0x{x}) start()", .{@intFromPtr(this)});
             this.ref();
             this.buffer = this.source.slice();
diff --git a/src/fd.zig b/src/fd.zig
index f92459eba9..85213862d8 100644
--- a/src/fd.zig
+++ b/src/fd.zig
@@ -595,7 +595,10 @@ pub const FD = packed struct(backing_int) {
     pub const truncate = bun.sys.ftruncate;
     pub const unlinkat = bun.sys.unlinkat;
     pub const updateNonblocking = bun.sys.updateNonblocking;
-    pub const write = bun.sys.write;
+    const Error = @import("./sys/Error.zig");
+    pub fn write(fd: bun.FileDescriptor, bytes: []const u8) bun.api.node.Maybe(usize, Error) {
+        return bun.sys.write(fd, bytes);
+    }
     pub const writeNonblocking = bun.sys.writeNonblocking;
     pub const writev = bun.sys.writev;
 
diff --git a/src/io/PipeReader.zig b/src/io/PipeReader.zig
index 628adf34e0..7a5ac5a289 100644
--- a/src/io/PipeReader.zig
+++ b/src/io/PipeReader.zig
@@ -1,3 +1,5 @@
+const mlog = @import("../mlog.zig").log;
+
 // This is a runtime type instead of comptime due to bugs in Zig.
 // https://github.com/ziglang/zig/issues/18664
 const BufferedReaderVTable = struct {
@@ -923,6 +925,7 @@ pub const WindowsBufferedReader = struct {
         const nread_int = nread.int();
 
         bun.sys.syslog("onStreamRead(0x{d}) = {d}", .{ @intFromPtr(this), nread_int });
+        mlog("onStreamRead(0x{d}) = {d}\n", .{ @intFromPtr(this), nread_int });
 
         // NOTE: pipes/tty need to call stopReading on errors (yeah)
         switch (nread_int) {
diff --git a/src/mlog.zig b/src/mlog.zig
new file mode 100644
index 0000000000..e29c8e2540
--- /dev/null
+++ b/src/mlog.zig
@@ -0,0 +1,70 @@
+const std = @import("std");
+const c = @cImport({
+    @cInclude("stdlib.h");
+});
+
+const Logger = struct {
+    var log_file: ?std.fs.File = null;
+    var proc_id: std.os.windows.DWORD = 0;
+    var name_buf: [64]u8 = undefined;
+    var name: []u8 = undefined;
+
+    export fn cleanup() void {
+        if (Logger.log_file) |*file| {
+            file.sync() catch {
+                @panic("Failed to flush mlog.txt: {any}\n");
+            };
+
+            file.close();
+            Logger.log_file = null;
+        }
+    }
+
+    fn getAndOpenFile() *std.fs.File {
+        if (Logger.log_file) |*file| {
+            return file;
+        }
+
+        Logger.proc_id = std.os.windows.GetCurrentProcessId();
+
+        var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+        defer _ = gpa.deinit();
+
+        var cwd = std.fs.cwd();
+
+        Logger.name = std.fmt.bufPrint(&name_buf, "mlog_{}.txt", .{Logger.proc_id}) catch {
+            @panic("Failed to format mlog filename: {any}\n");
+        };
+
+        Logger.log_file = cwd.openFile(Logger.name, .{
+            .mode = .read_write,
+        }) catch
+            cwd.createFile(
+                Logger.name,
+                .{
+                    .read = true,
+                    .truncate = true,
+                },
+            ) catch
+            @panic("Failed to create mlog.txt: {any}\n");
+
+        _ = c.atexit(cleanup);
+
+        return &(Logger.log_file orelse unreachable);
+    }
+
+    pub fn log(comptime fmt: []const u8, args: anytype) void {
+        const file = Logger.getAndOpenFile();
+
+        const writer = file.writer();
+
+        const nanos = std.time.nanoTimestamp();
+        std.fmt.format(writer, "[{}] (pid {}) " ++ fmt, .{ nanos, Logger.proc_id } ++ args) catch {
+            @panic("Failed to write to mlog.txt: {any}\n");
+        };
+
+        std.debug.print("Saved output to {s}.\n", .{name_buf});
+    }
+};
+
+pub const log = Logger.log;
diff --git a/src/shell/subproc.zig b/src/shell/subproc.zig
index dd308b13e7..5f94dfc163 100644
--- a/src/shell/subproc.zig
+++ b/src/shell/subproc.zig
@@ -1,3 +1,4 @@
+const mlog = @import("../mlog.zig").log;
 // const IPC = @import("../bun.js/ipc.zig");
 
 pub const Stdio = util.Stdio;
@@ -1135,6 +1136,7 @@ pub const PipeReader = struct {
         this.process = process;
         this.event_loop = event_loop;
         if (Environment.isWindows) {
+            mlog("Starting with current pipe...\n", .{});
             return this.reader.startWithCurrentPipe();
         }
 
@@ -1158,6 +1160,7 @@ pub const PipeReader = struct {
     pub const toJS = toReadableStream;
 
     pub fn onReadChunk(ptr: *anyopaque, chunk: []const u8, has_more: bun.io.ReadState) bool {
+        mlog("Reading a chunk...\n", .{});
         var this: *PipeReader = @ptrCast(@alignCast(ptr));
         this.buffered_output.append(chunk);
         log("PipeReader(0x{x}, {s}) onReadChunk(chunk_len={d}, has_more={s})", .{ @intFromPtr(this), @tagName(this.out_type), chunk.len, @tagName(has_more) });
@@ -1179,6 +1182,7 @@ pub const PipeReader = struct {
     }
 
     pub fn onReaderDone(this: *PipeReader) void {
+        mlog("The reader is done...\n", .{});
         log("onReaderDone(0x{x}, {s})", .{ @intFromPtr(this), @tagName(this.out_type) });
         const owned = this.toOwnedSlice();
         this.state = .{ .done = owned };
diff --git a/src/sys.zig b/src/sys.zig
index a800b68d42..93ea016825 100644
--- a/src/sys.zig
+++ b/src/sys.zig
@@ -4,6 +4,7 @@
 //!
 //! Sometimes this namespace is referred to as "Syscall", prefer "bun.sys"/"sys"
 
+const mlog = @import("./mlog.zig").log;
 const This = @This();
 
 //
@@ -1550,6 +1551,7 @@ pub fn write(fd: bun.FileDescriptor, bytes: []const u8) Maybe(usize) {
             // "WriteFile sets this value to zero before doing any work or error checking."
             var bytes_written: u32 = undefined;
             bun.assert(bytes.len > 0);
+            mlog("We're about to WriteFile({}, {})\n", .{ fd, adjusted_len });
             const rc = kernel32.WriteFile(
                 fd.cast(),
                 bytes.ptr,