--- isomaster-1.3.10.old/isomaster.h
+++ isomaster-1.3.10/isomaster.h
@@ -35,4 +35,12 @@
 #  define S_IFREG  0100000
 #endif
 
+#ifndef DEFAULT_EDITOR
+#define DEFAULT_EDITOR "leafpad"
+#endif
+
+#ifndef DEFAULT_VIEWER
+#define DEFAULT_VIEWER "sensible-browser"
+#endif
+
 #endif