diff --git a/build/bootstrap/ar.com b/build/bootstrap/ar.com
index 304bb55c3..25393e16f 100755
Binary files a/build/bootstrap/ar.com and b/build/bootstrap/ar.com differ
diff --git a/build/bootstrap/mkdeps.com b/build/bootstrap/mkdeps.com
index 5dbcfeec5..dd06f96b0 100755
Binary files a/build/bootstrap/mkdeps.com and b/build/bootstrap/mkdeps.com differ
diff --git a/build/bootstrap/package.com b/build/bootstrap/package.com
index b7a169cc6..c166f1018 100755
Binary files a/build/bootstrap/package.com and b/build/bootstrap/package.com differ
diff --git a/build/bootstrap/zipobj.com b/build/bootstrap/zipobj.com
index c9361bf7a..d148bd22d 100755
Binary files a/build/bootstrap/zipobj.com and b/build/bootstrap/zipobj.com differ
diff --git a/libc/calls/read-nt.c b/libc/calls/read-nt.c
index e1c86084e..024acb67b 100644
--- a/libc/calls/read-nt.c
+++ b/libc/calls/read-nt.c
@@ -26,35 +26,37 @@
 #include "libc/nt/struct/overlapped.h"
 #include "libc/sysv/errfuns.h"
 
+static textwindows ssize_t sys_read_nt_impl(struct Fd *fd, void *data,
+                                            size_t size, ssize_t offset) {
+  uint32_t got;
+  struct NtOverlapped overlap;
+  if (ReadFile(fd->handle, data, clampio(size), &got,
+               offset2overlap(offset, &overlap))) {
+    return got;
+  } else if (GetLastError() == kNtErrorBrokenPipe) {
+    return 0;
+  } else {
+    return __winerr();
+  }
+}
+
 textwindows ssize_t sys_read_nt(struct Fd *fd, const struct iovec *iov,
                                 size_t iovlen, ssize_t opt_offset) {
+  ssize_t rc;
+  uint32_t size;
   size_t i, total;
-  uint32_t got, size;
-  struct NtOverlapped overlap;
   while (iovlen && !iov[0].iov_len) iov++, iovlen--;
   if (iovlen) {
     for (total = i = 0; i < iovlen; ++i) {
-      size = clampio(iov[i].iov_len);
-      if (ReadFile(fd->handle, iov[i].iov_base, size, &got,
-                   offset2overlap(opt_offset, &overlap))) {
-        total += got;
-        if (opt_offset != -1) opt_offset += got;
-        if (got < iov[i].iov_len) break;
-      } else if (GetLastError() == kNtErrorBrokenPipe) {
-        break; /* read() doesn't EPIPE lool */
-      } else {
-        return __winerr();
-      }
+      if (!iov[i].iov_len) continue;
+      rc = sys_read_nt_impl(fd, iov[i].iov_base, iov[i].iov_len, opt_offset);
+      if (rc == -1) return -1;
+      total += rc;
+      if (opt_offset != -1) opt_offset += rc;
+      if (rc < iov[i].iov_len) break;
     }
     return total;
   } else {
-    if (ReadFile(fd->handle, NULL, 0, &got,
-                 offset2overlap(opt_offset, &overlap))) {
-      return got;
-    } else if (GetLastError() == kNtErrorBrokenPipe) {
-      return 0;
-    } else {
-      return __winerr();
-    }
+    return sys_read_nt_impl(fd, NULL, 0, opt_offset);
   }
 }
diff --git a/libc/calls/write-nt.c b/libc/calls/write-nt.c
index c2ebb80a9..5ae5a59b0 100644
--- a/libc/calls/write-nt.c
+++ b/libc/calls/write-nt.c
@@ -25,8 +25,22 @@
 #include "libc/nt/struct/overlapped.h"
 #include "libc/sysv/errfuns.h"
 
+static textwindows ssize_t sys_write_nt_impl(struct Fd *fd, void *data,
+                                             size_t size, ssize_t offset) {
+  uint32_t sent;
+  struct NtOverlapped overlap;
+  if (WriteFile(fd->handle, data, clampio(size), &sent,
+                offset2overlap(offset, &overlap))) {
+    /* TODO(jart): Trigger SIGPIPE on kNtErrorBrokenPipe */
+    return sent;
+  } else {
+    return __winerr();
+  }
+}
+
 textwindows ssize_t sys_write_nt(struct Fd *fd, const struct iovec *iov,
                                  size_t iovlen, ssize_t opt_offset) {
+  ssize_t rc;
   size_t i, total;
   uint32_t size, wrote;
   struct NtOverlapped overlap;
@@ -34,15 +48,11 @@ textwindows ssize_t sys_write_nt(struct Fd *fd, const struct iovec *iov,
   if (iovlen) {
     for (total = i = 0; i < iovlen; ++i) {
       if (!iov[i].iov_len) continue;
-      size = clampio(iov[0].iov_len);
-      if (WriteFile(fd->handle, iov[i].iov_base, size, &wrote,
-                    offset2overlap(opt_offset, &overlap))) {
-        total += wrote;
-        if (opt_offset != -1) opt_offset += wrote;
-        if (wrote < iov[i].iov_len) break;
-      } else {
-        return __winerr();
-      }
+      rc = sys_write_nt_impl(fd, iov[i].iov_base, iov[i].iov_len, opt_offset);
+      if (rc == -1) return -1;
+      total += rc;
+      if (opt_offset != -1) opt_offset += rc;
+      if (rc < iov[i].iov_len) break;
     }
     if (!total) assert(!__iovec_size(iov, iovlen));
     return total;
diff --git a/test/libc/calls/writev_test.c b/test/libc/calls/writev_test.c
new file mode 100644
index 000000000..0c712743a
--- /dev/null
+++ b/test/libc/calls/writev_test.c
@@ -0,0 +1,70 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2021 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/iovec.h"
+#include "libc/errno.h"
+#include "libc/macros.internal.h"
+#include "libc/sock/sock.h"
+#include "libc/sysv/consts/o.h"
+#include "libc/testlib/testlib.h"
+
+char testlib_enable_tmp_setup_teardown;
+
+TEST(writev, test) {
+  int fd;
+  char ba[1] = "a";
+  char bb[1] = "b";
+  char bc[2] = "cd";
+  struct iovec iov[] = {{"", 0}, {ba, 1}, {NULL, 0}, {bb, 1}, {bc, 2}};
+  ASSERT_NE(-1, (fd = open("file", O_RDWR | O_CREAT | O_TRUNC, 0644)));
+  EXPECT_EQ(4, writev(fd, iov, ARRAYLEN(iov)));
+  EXPECT_EQ(1, lseek(fd, 1, SEEK_SET));
+  EXPECT_EQ(3, readv(fd, iov, ARRAYLEN(iov)));
+  EXPECT_EQ('b', ba[0]);
+  EXPECT_EQ('c', bb[0]);
+  EXPECT_EQ('d', bc[0]);
+  EXPECT_NE(-1, close(fd));
+}
+
+TEST(writev, big_fullCompletion) {
+  int fd;
+  char *ba = malloc(2 * 1024 * 1024);
+  char *bb = malloc(2 * 1024 * 1024);
+  char *bc = malloc(2 * 1024 * 1024);
+  struct iovec iov[] = {
+      {"", 0},                //
+      {ba, 2 * 1024 * 1024},  //
+      {NULL, 0},              //
+      {bb, 2 * 1024 * 1024},  //
+      {bc, 2 * 1024 * 1024},  //
+  };
+  ASSERT_NE(-1, (fd = open("file", O_RDWR | O_CREAT | O_TRUNC, 0644)));
+  EXPECT_EQ(6 * 1024 * 1024, writev(fd, iov, ARRAYLEN(iov)));
+  EXPECT_NE(-1, close(fd));
+}
+
+TEST(writev, empty_stillPerformsIoOperation) {
+  int fd;
+  struct iovec iov[] = {{"", 0}, {NULL, 0}};
+  ASSERT_NE(-1, touch("file", 0644));
+  ASSERT_NE(-1, (fd = open("file", O_RDONLY)));
+  EXPECT_EQ(-1, writev(fd, iov, ARRAYLEN(iov)));
+  EXPECT_EQ(-1, writev(fd, NULL, 0));
+  EXPECT_NE(-1, close(fd));
+}
diff --git a/test/libc/stdio/spawn_test.c b/test/libc/stdio/spawn_test.c
index b03c8c9ff..c834a6a9c 100644
--- a/test/libc/stdio/spawn_test.c
+++ b/test/libc/stdio/spawn_test.c
@@ -61,7 +61,7 @@ const char kTinyLinuxExit[128] = {
     0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00,  // ⌂ELF☻☺☺ 
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  //         
     0x02, 0x00, 0x3e, 0x00, 0x01, 0x00, 0x00, 0x00,  // ☻ > ☺   
-    0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,  //  x @     
+    0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,  // x @     
     0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  // @       
     0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  //         
     0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00,  //     @ 8