diff -r 235ff1c046df src/base/output.cc
--- a/src/base/output.cc	Fri Apr 03 11:42:11 2015 -0500
+++ b/src/base/output.cc	Thu Apr 09 10:26:58 2015 +0100
@@ -33,6 +33,10 @@
 #include <sys/types.h>
 #include <dirent.h>
 
+#if defined(__FreeBSD__)
+#include <unistd.h>
+#endif
+
 #include <cassert>
 #include <cerrno>
 #include <climits>