diff --git a/windows/exec_windows.go b/windows/exec_windows.go
index 924775b8..9eb1fb63 100644
--- a/windows/exec_windows.go
+++ b/windows/exec_windows.go
@@ -111,7 +111,9 @@ func NewProcThreadAttributeList(maxAttrCount uint32) (*ProcThreadAttributeList,
 		}
 		return nil, err
 	}
-	al := (*ProcThreadAttributeList)(unsafe.Pointer(&make([]byte, size)[0]))
+	const psize = unsafe.Sizeof(uintptr(0))
+	// size is guaranteed to be ≥1 by InitializeProcThreadAttributeList.
+	al := (*ProcThreadAttributeList)(unsafe.Pointer(&make([]unsafe.Pointer, (size+psize-1)/psize)[0]))
 	err = initializeProcThreadAttributeList(al, maxAttrCount, 0, &size)
 	if err != nil {
 		return nil, err
@@ -120,8 +122,8 @@ func NewProcThreadAttributeList(maxAttrCount uint32) (*ProcThreadAttributeList,
 }
 
 // Update modifies the ProcThreadAttributeList using UpdateProcThreadAttribute.
-func (al *ProcThreadAttributeList) Update(attribute uintptr, flags uint32, value unsafe.Pointer, size uintptr, prevValue uintptr, returnedSize *uintptr) error {
-	return updateProcThreadAttribute(al, flags, attribute, uintptr(value), size, prevValue, returnedSize)
+func (al *ProcThreadAttributeList) Update(attribute uintptr, flags uint32, value unsafe.Pointer, size uintptr, prevValue unsafe.Pointer, returnedSize *uintptr) error {
+	return updateProcThreadAttribute(al, flags, attribute, value, size, prevValue, returnedSize)
 }
 
 // Delete frees ProcThreadAttributeList's resources.
diff --git a/windows/syscall_windows.go b/windows/syscall_windows.go
index 38d7d58b..376dd070 100644
--- a/windows/syscall_windows.go
+++ b/windows/syscall_windows.go
@@ -216,7 +216,7 @@ func NewCallbackCDecl(fn interface{}) uintptr {
 //sys	CreateProcess(appName *uint16, commandLine *uint16, procSecurity *SecurityAttributes, threadSecurity *SecurityAttributes, inheritHandles bool, creationFlags uint32, env *uint16, currentDir *uint16, startupInfo *StartupInfo, outProcInfo *ProcessInformation) (err error) = CreateProcessW
 //sys   initializeProcThreadAttributeList(attrlist *ProcThreadAttributeList, attrcount uint32, flags uint32, size *uintptr) (err error) = InitializeProcThreadAttributeList
 //sys   deleteProcThreadAttributeList(attrlist *ProcThreadAttributeList) = DeleteProcThreadAttributeList
-//sys   updateProcThreadAttribute(attrlist *ProcThreadAttributeList, flags uint32, attr uintptr, value uintptr, size uintptr, prevvalue uintptr, returnedsize *uintptr) (err error) = UpdateProcThreadAttribute
+//sys   updateProcThreadAttribute(attrlist *ProcThreadAttributeList, flags uint32, attr uintptr, value unsafe.Pointer, size uintptr, prevvalue unsafe.Pointer, returnedsize *uintptr) (err error) = UpdateProcThreadAttribute
 //sys	OpenProcess(desiredAccess uint32, inheritHandle bool, processId uint32) (handle Handle, err error)
 //sys	ShellExecute(hwnd Handle, verb *uint16, file *uint16, args *uint16, cwd *uint16, showCmd int32) (err error) [failretval<=32] = shell32.ShellExecuteW
 //sys	GetWindowThreadProcessId(hwnd HWND, pid *uint32) (tid uint32, err error) = user32.GetWindowThreadProcessId
diff --git a/windows/syscall_windows_test.go b/windows/syscall_windows_test.go
index a3d5a873..34315460 100644
--- a/windows/syscall_windows_test.go
+++ b/windows/syscall_windows_test.go
@@ -16,6 +16,7 @@ import (
 	"strings"
 	"syscall"
 	"testing"
+	"time"
 	"unsafe"
 
 	"golang.org/x/sys/windows"
@@ -502,3 +503,36 @@ func TestNTStatusConversion(t *testing.T) {
 		t.Errorf("NTStatus.Errno = %q (0x%x); want %q (0x%x)", got.Error(), got, want.Error(), want)
 	}
 }
+
+func TestProcThreadAttributeListPointers(t *testing.T) {
+	list, err := windows.NewProcThreadAttributeList(1)
+	if err != nil {
+		t.Errorf("unable to create ProcThreadAttributeList: %v", err)
+	}
+	done := make(chan struct{})
+	fds := make([]syscall.Handle, 20)
+	runtime.SetFinalizer(&fds[0], func(*syscall.Handle) {
+		close(done)
+	})
+	err = list.Update(windows.PROC_THREAD_ATTRIBUTE_HANDLE_LIST, 0, unsafe.Pointer(&fds[0]), uintptr(len(fds))*unsafe.Sizeof(fds[0]), nil, nil)
+	if err != nil {
+		list.Delete()
+		t.Errorf("unable to update ProcThreadAttributeList: %v", err)
+		return
+	}
+	runtime.GC()
+	runtime.GC()
+	select {
+	case <-done:
+		t.Error("ProcThreadAttributeList was garbage collected unexpectedly")
+	default:
+	}
+	list.Delete()
+	runtime.GC()
+	runtime.GC()
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Error("ProcThreadAttributeList was not garbage collected after a second")
+	}
+}
diff --git a/windows/types_windows.go b/windows/types_windows.go
index d2e0745e..abefd93a 100644
--- a/windows/types_windows.go
+++ b/windows/types_windows.go
@@ -912,7 +912,11 @@ type StartupInfoEx struct {
 // To create a *ProcThreadAttributeList, use NewProcThreadAttributeList, and
 // free its memory using ProcThreadAttributeList.Delete.
 type ProcThreadAttributeList struct {
-	_ [1]byte
+	// This is of type unsafe.Pointer, not of type byte or uintptr, because
+	// the contents of it is mostly a list of pointers, and in most cases,
+	// that's a list of pointers to Go-allocated objects. In order to keep
+	// the GC from collecting these objects, we declare this as unsafe.Pointer.
+	_ [1]unsafe.Pointer
 }
 
 type ProcessInformation struct {
diff --git a/windows/zsyscall_windows.go b/windows/zsyscall_windows.go
index 8b16cb35..6f16452c 100644
--- a/windows/zsyscall_windows.go
+++ b/windows/zsyscall_windows.go
@@ -2811,7 +2811,7 @@ func UnmapViewOfFile(addr uintptr) (err error) {
 	return
 }
 
-func updateProcThreadAttribute(attrlist *ProcThreadAttributeList, flags uint32, attr uintptr, value uintptr, size uintptr, prevvalue uintptr, returnedsize *uintptr) (err error) {
+func updateProcThreadAttribute(attrlist *ProcThreadAttributeList, flags uint32, attr uintptr, value unsafe.Pointer, size uintptr, prevvalue unsafe.Pointer, returnedsize *uintptr) (err error) {
 	r1, _, e1 := syscall.Syscall9(procUpdateProcThreadAttribute.Addr(), 7, uintptr(unsafe.Pointer(attrlist)), uintptr(flags), uintptr(attr), uintptr(value), uintptr(size), uintptr(prevvalue), uintptr(unsafe.Pointer(returnedsize)), 0, 0)
 	if r1 == 0 {
 		err = errnoErr(e1)