diff --git a/fileserver/sync_api.go b/fileserver/sync_api.go
index acbad47a..dd6c7883 100644
--- a/fileserver/sync_api.go
+++ b/fileserver/sync_api.go
@@ -827,7 +827,7 @@ func putSendBlockCB(rsp http.ResponseWriter, r *http.Request) *appError {
 	}
 
 	if err := blockmgr.Write(storeID, blockID, r.Body); err != nil {
-		err := fmt.Errorf("Failed to close block %.8s:%s", storeID, blockID)
+		err := fmt.Errorf("Failed to write block %.8s:%s: %v", storeID, blockID, err)
 		return &appError{err, "", http.StatusInternalServerError}
 	}