diff -Naurp1 a/src/Config.cxx b/src/Config.cxx
--- a/src/Config.cxx	2011-05-28 16:25:01.000000000 +0600
+++ b/src/Config.cxx	2020-10-21 14:41:46.814972000 +0600
@@ -24,3 +24,3 @@ using namespace ePDFView;
 // Constants
-static const gchar *DEFAULT_EXTERNAL_BROWSER_COMMAND_LINE = "firefox %s";
+static const gchar *DEFAULT_EXTERNAL_BROWSER_COMMAND_LINE = "xdg-open %s";
 static const gchar *DEFAULT_OPEN_FILE_FOLDER = NULL;
