diff --git a/lib/ssh.c b/lib/ssh.c
index 026212103e..314d898431 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -1442,6 +1442,11 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
             data->state.resume_from = 0;
           }
           else {
+            curl_off_t size = attrs.filesize;
+            if(size < 0) {
+              failf(data, "Bad file size (%" FORMAT_OFF_T ")", size);
+              return CURLE_BAD_DOWNLOAD_RESUME;
+            }
             data->state.resume_from = attrs.filesize;
           }
         }