diff -ur zdoom-2.6.1.orig/src/gameconfigfile.cpp zdoom-2.6.1/src/gameconfigfile.cpp
--- zdoom-2.6.1.orig/src/gameconfigfile.cpp	2012-07-02 00:49:26.000000000 +0200
+++ zdoom-2.6.1/src/gameconfigfile.cpp	2012-07-29 16:23:11.755232082 +0200
@@ -140,6 +140,7 @@
 #else
 		SetValueForKey ("Path", "~/" GAME_DIR, true);
 		SetValueForKey ("Path", SHARE_DIR, true);
+		SetValueForKey ("Path", "/usr/share/doom", true);
 #endif
 	}