diff -up asymptote-2.67/settings.cc.settings asymptote-2.67/settings.cc
--- asymptote-2.67/settings.cc.settings	2020-08-06 11:49:53.902137481 -0400
+++ asymptote-2.67/settings.cc	2020-08-06 11:51:55.500637009 -0400
@@ -100,9 +100,9 @@ string defaultPSViewer="open";
 string defaultPDFViewer="open";
 string defaultHTMLViewer="open";
 #else
-string defaultPSViewer="gv";
-string defaultPDFViewer="acroread";
-string defaultHTMLViewer="google-chrome";
+string defaultPSViewer="evince";
+string defaultPDFViewer="evince";
+string defaultHTMLViewer="xdg-open";
 #endif
 string defaultGhostscript="gs";
 string defaultGhostscriptLibrary="";
