diff --git a/pub/src/dualplot.cpp b/pub/src/dualplot.cpp
index 0c8138b1c12414237d4414278545d9908fd723e5..56a0bcd03df01cde7702e561abf3cc55725c2133 100644
--- a/pub/src/dualplot.cpp
+++ b/pub/src/dualplot.cpp
@@ -397,7 +397,7 @@ void CPlot::addScan( bool as_line, int style_no,
     if ( np!=yp.size() )
         throw string( "PROG ERR NPLot::Line x.size<>y.size" );
 
-    // Data to tmp file:
+    // Prepare for live display, to be shown by showScans():
     string gp_fnam = str( format( "/tmp/%s-%d-%03d.gnu" )
                           % getenv("LOGNAME") % iPlot % gp_fno++ );
     if (gp_fnames!="") gp_fnames += ", ";