diff --git a/backend/local/local.go b/backend/local/local.go
index 7721d1edf..5e5369e74 100644
--- a/backend/local/local.go
+++ b/backend/local/local.go
@@ -1068,6 +1068,12 @@ func (f *Fs) OpenWriterAt(ctx context.Context, remote string, size int64) (fs.Wr
 	if err != nil {
 		fs.Debugf(o, "Failed to pre-allocate: %v", err)
 	}
+	// Set the file to be a sparse file (important on Windows)
+	err = setSparse(out)
+	if err != nil {
+		fs.Debugf(o, "Failed to set sparse: %v", err)
+	}
+
 	return out, nil
 }
 
diff --git a/backend/local/preallocate_other.go b/backend/local/preallocate_other.go
index fb71cad59..5738b485c 100644
--- a/backend/local/preallocate_other.go
+++ b/backend/local/preallocate_other.go
@@ -8,3 +8,8 @@ import "os"
 func preAllocate(size int64, out *os.File) error {
 	return nil
 }
+
+// setSparse makes the file be a sparse file
+func setSparse(out *os.File) error {
+	return nil
+}
diff --git a/backend/local/preallocate_unix.go b/backend/local/preallocate_unix.go
index 5caf6c1e4..e7472f6a7 100644
--- a/backend/local/preallocate_unix.go
+++ b/backend/local/preallocate_unix.go
@@ -44,3 +44,8 @@ again:
 	// }
 	return err
 }
+
+// setSparse makes the file be a sparse file
+func setSparse(out *os.File) error {
+	return nil
+}
diff --git a/backend/local/preallocate_windows.go b/backend/local/preallocate_windows.go
index dfd88369d..a434272f7 100644
--- a/backend/local/preallocate_windows.go
+++ b/backend/local/preallocate_windows.go
@@ -77,3 +77,16 @@ func preAllocate(size int64, out *os.File) error {
 
 	return nil
 }
+
+const (
+	FSCTL_SET_SPARSE = 0x000900c4
+)
+
+// setSparse makes the file be a sparse file
+func setSparse(out *os.File) error {
+	err := syscall.DeviceIoControl(syscall.Handle(out.Fd()), FSCTL_SET_SPARSE, nil, 0, nil, 0, nil, nil)
+	if err != nil {
+		return errors.Wrap(err, "DeviceIoControl FSCTL_SET_SPARSE")
+	}
+	return nil
+}