Index: src/scripts/src/lualib/lobject.h
===================================================================
--- src/scripts/src/lualib/lobject.h    (revision 4422)
+++ src/scripts/src/lualib/lobject.h    (working copy)
@@ -100,7 +100,7 @@
 #define bvalue(o)  check_exp(ttisboolean(o), (o)->value.b)
 #define thvalue(o) check_exp(ttisthread(o), &(o)->value.gc->th)

-#define l_isfalse(o)   (ttisnil(o) || (ttisboolean(o) && bvalue(o) == 0))
+#define l_isfalse(o)   (ttisnil(o) || (ttisboolean(o) && bvalue(o) == 0) || (ttisnumber(o) && nvalue(o) == 0))

 /*
 ** for internal debug only