diff --git a/lib/xwrap.c b/lib/xwrap.c
index cc320af8..6a910230 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -867,9 +867,9 @@ long long xsendfile_len(int in, int out, long long bytes)
 {
   long long len = sendfile_len(in, out, bytes, 0);
 
-  if (bytes != -1 && bytes != len) {
+  if (len == -1 || (bytes != -1 && bytes != len)) {
     if (out == 1 && len<0) xexit();
-    error_exit("short %s", (len<0) ? "write" : "read");
+    perror_exit("short %s", (len<0) ? "write" : "read");
   }
 
   return len;