diff --git a/pkg/provider/crypto/file.go b/pkg/provider/crypto/file.go
index 2fa848d..305d482 100644
--- a/pkg/provider/crypto/file.go
+++ b/pkg/provider/crypto/file.go
@@ -199,6 +199,9 @@ func (f *file) WriteAt(data []byte, pos int64) (n int, err error) {
 		w, e := c.writeAt(data[n:], woff)
 		n += w
 		if c.full() {
+			if f.w.last.cn == cn {
+				f.w.last = nil
+			}
 			// async flush
 			go func() {
 				c.flush(notLastChunk)