Index: libs/iovm/source/IoNumber.c
--- libs/iovm/source/IoNumber.c.orig	2008-03-30 06:16:50 +0200
+++ libs/iovm/source/IoNumber.c	2010-01-10 14:06:46 +0100
@@ -37,6 +37,10 @@
 #define isnan _isnan
 #endif
 
+#ifdef __FreeBSD__
+#define log2(x) (log(x) / M_LN2)
+#endif
+
 #define DATA(self) CNUMBER(self)
 
 IoNumber *IoNumber_numberForDouble_canUse_(IoNumber *self, double n, IoNumber *other)
