diff --git a/pub/lib/plot.cpp b/pub/lib/plot.cpp
index aaa6abecfd80dcf43ab8b02ac864564579efbad9..43d23ce18eb9a11c8b48e5ffc3469ea5490fb139 100644
--- a/pub/lib/plot.cpp
+++ b/pub/lib/plot.cpp
@@ -386,6 +386,7 @@ namespace {
             if (po.size()==nout)
                 break;
             nout = po.size();
+            pp = po;
         }
 
         // divide into segments