diff --git a/backend/box/upload.go b/backend/box/upload.go
index 3afad813e..2a1e8e6a1 100644
--- a/backend/box/upload.go
+++ b/backend/box/upload.go
@@ -112,7 +112,7 @@ outer:
 			return shouldRetry(resp, err)
 		})
 		delay := defaultDelay
-		why := "unknown"
+		var why string
 		if err != nil {
 			// Sometimes we get 400 Error with
 			// parts_mismatch immediately after uploading