diff -up mm3d-1.3.8a/src/libmm3d/misc.cc.unistd mm3d-1.3.8a/src/libmm3d/misc.cc
--- mm3d-1.3.8a/src/libmm3d/misc.cc.unistd	2012-01-15 12:18:43.000000000 +0100
+++ mm3d-1.3.8a/src/libmm3d/misc.cc	2012-01-15 12:18:53.000000000 +0100
@@ -39,6 +39,7 @@
 #include <sys/stat.h>
 #include <ctype.h>
 #include <errno.h>
+#include <unistd.h>
 
 using std::string;