diff --git a/src/d_main.cpp b/src/d_main.cpp
index 9c76bd9990..eec2f21967 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -646,6 +646,7 @@ CVAR (Flag, compat_pushwindow,			compatflags2, COMPATF2_PUSHWINDOW);
 CVAR (Flag, compat_checkswitchrange,	compatflags2, COMPATF2_CHECKSWITCHRANGE);
 CVAR (Flag, compat_explode1,			compatflags2, COMPATF2_EXPLODE1);
 CVAR (Flag, compat_explode2,			compatflags2, COMPATF2_EXPLODE2);
+CVAR (Flag, compat_railing,				compatflags2, COMPATF2_RAILING);
 
 CVAR(Bool, vid_activeinbackground, false, CVAR_ARCHIVE | CVAR_GLOBALCONFIG)