diff -up asymptote-2.55/settings.cc.settings asymptote-2.55/settings.cc
--- asymptote-2.55/settings.cc.settings 2019-09-30 06:47:32.464160386 -0400
+++ asymptote-2.55/settings.cc 2019-09-30 06:48:48.419518013 -0400
@@ -98,9 +98,9 @@ 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="chromium";
#endif
string defaultGhostscript="gs";
string defaultGhostscriptLibrary="";