diff --git a/backup.go b/backup.go
index ceedee1..27d6ace 100644
--- a/backup.go
+++ b/backup.go
@@ -185,7 +185,6 @@ type BackupFileReader struct {
 // Read will attempt to read the security descriptor of the file.
 func NewBackupFileReader(f *os.File, includeSecurity bool) *BackupFileReader {
 	r := &BackupFileReader{f, includeSecurity, 0}
-	runtime.SetFinalizer(r, func(r *BackupFileReader) { r.Close() })
 	return r
 }
 
@@ -196,6 +195,7 @@ func (r *BackupFileReader) Read(b []byte) (int, error) {
 	if err != nil {
 		return 0, &os.PathError{"BackupRead", r.f.Name(), err}
 	}
+	runtime.KeepAlive(r.f)
 	if bytesRead == 0 {
 		return 0, io.EOF
 	}
@@ -207,6 +207,7 @@ func (r *BackupFileReader) Read(b []byte) (int, error) {
 func (r *BackupFileReader) Close() error {
 	if r.ctx != 0 {
 		backupRead(syscall.Handle(r.f.Fd()), nil, nil, true, false, &r.ctx)
+		runtime.KeepAlive(r.f)
 		r.ctx = 0
 	}
 	return nil
@@ -223,7 +224,6 @@ type BackupFileWriter struct {
 // Write() will attempt to restore the security descriptor from the stream.
 func NewBackupFileWriter(f *os.File, includeSecurity bool) *BackupFileWriter {
 	w := &BackupFileWriter{f, includeSecurity, 0}
-	runtime.SetFinalizer(w, func(w *BackupFileWriter) { w.Close() })
 	return w
 }
 
@@ -234,6 +234,7 @@ func (w *BackupFileWriter) Write(b []byte) (int, error) {
 	if err != nil {
 		return 0, &os.PathError{"BackupWrite", w.f.Name(), err}
 	}
+	runtime.KeepAlive(w.f)
 	if int(bytesWritten) != len(b) {
 		return int(bytesWritten), errors.New("not all bytes could be written")
 	}
@@ -245,6 +246,7 @@ func (w *BackupFileWriter) Write(b []byte) (int, error) {
 func (w *BackupFileWriter) Close() error {
 	if w.ctx != 0 {
 		backupWrite(syscall.Handle(w.f.Fd()), nil, nil, true, false, &w.ctx)
+		runtime.KeepAlive(w.f)
 		w.ctx = 0
 	}
 	return nil
diff --git a/file.go b/file.go
index 231863c..b955e88 100644
--- a/file.go
+++ b/file.go
@@ -79,7 +79,6 @@ func makeWin32File(h syscall.Handle) (*win32File, error) {
 	if err != nil {
 		return nil, err
 	}
-	runtime.SetFinalizer(f, (*win32File).closeHandle)
 	return f, nil
 }
 
@@ -103,7 +102,6 @@ func (f *win32File) closeHandle() {
 // Close closes a win32File.
 func (f *win32File) Close() error {
 	f.closeHandle()
-	runtime.SetFinalizer(f, nil)
 	return nil
 }
 
@@ -166,6 +164,12 @@ func (f *win32File) asyncIo(c *ioOperation, deadline time.Time, bytes uint32, er
 		if wait {
 			r = <-c.ch
 		}
+
+		// runtime.KeepAlive is needed, as c is passed via native
+		// code to ioCompletionProcessor, c must remain alive
+		// until the channel read is complete.
+		runtime.KeepAlive(c)
+
 		err = r.err
 		if err == syscall.ERROR_OPERATION_ABORTED {
 			if f.closing {
@@ -188,6 +192,7 @@ func (f *win32File) Read(b []byte) (int, error) {
 	var bytes uint32
 	err = syscall.ReadFile(f.handle, b, &bytes, &c.o)
 	n, err := f.asyncIo(c, f.readDeadline, bytes, err)
+	runtime.KeepAlive(b)
 
 	// Handle EOF conditions.
 	if err == nil && n == 0 && len(b) != 0 {
@@ -207,7 +212,9 @@ func (f *win32File) Write(b []byte) (int, error) {
 	}
 	var bytes uint32
 	err = syscall.WriteFile(f.handle, b, &bytes, &c.o)
-	return f.asyncIo(c, f.writeDeadline, bytes, err)
+	n, err := f.asyncIo(c, f.writeDeadline, bytes, err)
+	runtime.KeepAlive(b)
+	return n, err
 }
 
 func (f *win32File) SetReadDeadline(t time.Time) error {
diff --git a/fileinfo.go b/fileinfo.go
index a822e43..b1d60ab 100644
--- a/fileinfo.go
+++ b/fileinfo.go
@@ -4,6 +4,7 @@ package winio
 
 import (
 	"os"
+	"runtime"
 	"syscall"
 	"unsafe"
 )
@@ -28,6 +29,7 @@ func GetFileBasicInfo(f *os.File) (*FileBasicInfo, error) {
 	if err := getFileInformationByHandleEx(syscall.Handle(f.Fd()), fileBasicInfo, (*byte)(unsafe.Pointer(bi)), uint32(unsafe.Sizeof(*bi))); err != nil {
 		return nil, &os.PathError{Op: "GetFileInformationByHandleEx", Path: f.Name(), Err: err}
 	}
+	runtime.KeepAlive(f)
 	return bi, nil
 }
 
@@ -36,6 +38,7 @@ func SetFileBasicInfo(f *os.File, bi *FileBasicInfo) error {
 	if err := setFileInformationByHandle(syscall.Handle(f.Fd()), fileBasicInfo, (*byte)(unsafe.Pointer(bi)), uint32(unsafe.Sizeof(*bi))); err != nil {
 		return &os.PathError{Op: "SetFileInformationByHandle", Path: f.Name(), Err: err}
 	}
+	runtime.KeepAlive(f)
 	return nil
 }
 
@@ -52,5 +55,6 @@ func GetFileID(f *os.File) (*FileIDInfo, error) {
 	if err := getFileInformationByHandleEx(syscall.Handle(f.Fd()), fileIDInfo, (*byte)(unsafe.Pointer(fileID)), uint32(unsafe.Sizeof(*fileID))); err != nil {
 		return nil, &os.PathError{Op: "GetFileInformationByHandleEx", Path: f.Name(), Err: err}
 	}
+	runtime.KeepAlive(f)
 	return fileID, nil
 }
diff --git a/zsyscall_windows.go b/zsyscall_windows.go
index c5e369b..039daaa 100644
--- a/zsyscall_windows.go
+++ b/zsyscall_windows.go
@@ -11,6 +11,31 @@ import (
 
 var _ unsafe.Pointer
 
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return nil
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
 var (
 	modkernel32 = windows.NewLazySystemDLL("kernel32.dll")
 	modwinmm    = windows.NewLazySystemDLL("winmm.dll")
@@ -51,7 +76,7 @@ func cancelIoEx(file syscall.Handle, o *syscall.Overlapped) (err error) {
 	r1, _, e1 := syscall.Syscall(procCancelIoEx.Addr(), 2, uintptr(file), uintptr(unsafe.Pointer(o)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -64,7 +89,7 @@ func createIoCompletionPort(file syscall.Handle, port syscall.Handle, key uintpt
 	newport = syscall.Handle(r0)
 	if newport == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -76,7 +101,7 @@ func getQueuedCompletionStatus(port syscall.Handle, bytes *uint32, key *uintptr,
 	r1, _, e1 := syscall.Syscall6(procGetQueuedCompletionStatus.Addr(), 5, uintptr(port), uintptr(unsafe.Pointer(bytes)), uintptr(unsafe.Pointer(key)), uintptr(unsafe.Pointer(o)), uintptr(timeout), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -88,7 +113,7 @@ func setFileCompletionNotificationModes(h syscall.Handle, flags uint8) (err erro
 	r1, _, e1 := syscall.Syscall(procSetFileCompletionNotificationModes.Addr(), 2, uintptr(h), uintptr(flags), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -106,7 +131,7 @@ func connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) {
 	r1, _, e1 := syscall.Syscall(procConnectNamedPipe.Addr(), 2, uintptr(pipe), uintptr(unsafe.Pointer(o)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -128,7 +153,7 @@ func _createNamedPipe(name *uint16, flags uint32, pipeMode uint32, maxInstances
 	handle = syscall.Handle(r0)
 	if handle == syscall.InvalidHandle {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -150,7 +175,7 @@ func _createFile(name *uint16, access uint32, mode uint32, sa *securityAttribute
 	handle = syscall.Handle(r0)
 	if handle == syscall.InvalidHandle {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -171,7 +196,7 @@ func _waitNamedPipe(name *uint16, timeout uint32) (err error) {
 	r1, _, e1 := syscall.Syscall(procWaitNamedPipeW.Addr(), 2, uintptr(unsafe.Pointer(name)), uintptr(timeout), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -183,7 +208,7 @@ func getNamedPipeInfo(pipe syscall.Handle, flags *uint32, outSize *uint32, inSiz
 	r1, _, e1 := syscall.Syscall6(procGetNamedPipeInfo.Addr(), 5, uintptr(pipe), uintptr(unsafe.Pointer(flags)), uintptr(unsafe.Pointer(outSize)), uintptr(unsafe.Pointer(inSize)), uintptr(unsafe.Pointer(maxInstances)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -195,7 +220,7 @@ func getNamedPipeHandleState(pipe syscall.Handle, state *uint32, curInstances *u
 	r1, _, e1 := syscall.Syscall9(procGetNamedPipeHandleStateW.Addr(), 7, uintptr(pipe), uintptr(unsafe.Pointer(state)), uintptr(unsafe.Pointer(curInstances)), uintptr(unsafe.Pointer(maxCollectionCount)), uintptr(unsafe.Pointer(collectDataTimeout)), uintptr(unsafe.Pointer(userName)), uintptr(maxUserNameSize), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -216,7 +241,7 @@ func _lookupAccountName(systemName *uint16, accountName *uint16, sid *byte, sidS
 	r1, _, e1 := syscall.Syscall9(procLookupAccountNameW.Addr(), 7, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(accountName)), uintptr(unsafe.Pointer(sid)), uintptr(unsafe.Pointer(sidSize)), uintptr(unsafe.Pointer(refDomain)), uintptr(unsafe.Pointer(refDomainSize)), uintptr(unsafe.Pointer(sidNameUse)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -228,7 +253,7 @@ func convertSidToStringSid(sid *byte, str **uint16) (err error) {
 	r1, _, e1 := syscall.Syscall(procConvertSidToStringSidW.Addr(), 2, uintptr(unsafe.Pointer(sid)), uintptr(unsafe.Pointer(str)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -249,7 +274,7 @@ func _convertStringSecurityDescriptorToSecurityDescriptor(str *uint16, revision
 	r1, _, e1 := syscall.Syscall6(procConvertStringSecurityDescriptorToSecurityDescriptorW.Addr(), 4, uintptr(unsafe.Pointer(str)), uintptr(revision), uintptr(unsafe.Pointer(sd)), uintptr(unsafe.Pointer(size)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -261,7 +286,7 @@ func convertSecurityDescriptorToStringSecurityDescriptor(sd *byte, revision uint
 	r1, _, e1 := syscall.Syscall6(procConvertSecurityDescriptorToStringSecurityDescriptorW.Addr(), 5, uintptr(unsafe.Pointer(sd)), uintptr(revision), uintptr(secInfo), uintptr(unsafe.Pointer(sddl)), uintptr(unsafe.Pointer(sddlSize)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -284,7 +309,7 @@ func getFileInformationByHandleEx(h syscall.Handle, class uint32, buffer *byte,
 	r1, _, e1 := syscall.Syscall6(procGetFileInformationByHandleEx.Addr(), 4, uintptr(h), uintptr(class), uintptr(unsafe.Pointer(buffer)), uintptr(size), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -296,7 +321,7 @@ func setFileInformationByHandle(h syscall.Handle, class uint32, buffer *byte, si
 	r1, _, e1 := syscall.Syscall6(procSetFileInformationByHandle.Addr(), 4, uintptr(h), uintptr(class), uintptr(unsafe.Pointer(buffer)), uintptr(size), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -315,7 +340,7 @@ func adjustTokenPrivileges(token windows.Token, releaseAll bool, input *byte, ou
 	success = r0 != 0
 	if true {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -327,7 +352,7 @@ func impersonateSelf(level uint32) (err error) {
 	r1, _, e1 := syscall.Syscall(procImpersonateSelf.Addr(), 1, uintptr(level), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -339,7 +364,7 @@ func revertToSelf() (err error) {
 	r1, _, e1 := syscall.Syscall(procRevertToSelf.Addr(), 0, 0, 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -357,7 +382,7 @@ func openThreadToken(thread syscall.Handle, accessMask uint32, openAsSelf bool,
 	r1, _, e1 := syscall.Syscall6(procOpenThreadToken.Addr(), 4, uintptr(thread), uintptr(accessMask), uintptr(_p0), uintptr(unsafe.Pointer(token)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -389,7 +414,7 @@ func _lookupPrivilegeValue(systemName *uint16, name *uint16, luid *uint64) (err
 	r1, _, e1 := syscall.Syscall(procLookupPrivilegeValueW.Addr(), 3, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(luid)))
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -410,7 +435,7 @@ func _lookupPrivilegeName(systemName *uint16, luid *uint64, buffer *uint16, size
 	r1, _, e1 := syscall.Syscall6(procLookupPrivilegeNameW.Addr(), 4, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(luid)), uintptr(unsafe.Pointer(buffer)), uintptr(unsafe.Pointer(size)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -431,7 +456,7 @@ func _lookupPrivilegeDisplayName(systemName *uint16, name *uint16, buffer *uint1
 	r1, _, e1 := syscall.Syscall6(procLookupPrivilegeDisplayNameW.Addr(), 5, uintptr(unsafe.Pointer(systemName)), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(buffer)), uintptr(unsafe.Pointer(size)), uintptr(unsafe.Pointer(languageId)), 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -459,7 +484,7 @@ func backupRead(h syscall.Handle, b []byte, bytesRead *uint32, abort bool, proce
 	r1, _, e1 := syscall.Syscall9(procBackupRead.Addr(), 7, uintptr(h), uintptr(unsafe.Pointer(_p0)), uintptr(len(b)), uintptr(unsafe.Pointer(bytesRead)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(context)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}
@@ -487,7 +512,7 @@ func backupWrite(h syscall.Handle, b []byte, bytesWritten *uint32, abort bool, p
 	r1, _, e1 := syscall.Syscall9(procBackupWrite.Addr(), 7, uintptr(h), uintptr(unsafe.Pointer(_p0)), uintptr(len(b)), uintptr(unsafe.Pointer(bytesWritten)), uintptr(_p1), uintptr(_p2), uintptr(unsafe.Pointer(context)), 0, 0)
 	if r1 == 0 {
 		if e1 != 0 {
-			err = error(e1)
+			err = errnoErr(e1)
 		} else {
 			err = syscall.EINVAL
 		}