diff -up jam/jam.h jam_/jam.h
--- jam/jam.h	Sat Jan  4 06:14:02 2014
+++ jam_/jam.h	Sat Jan  4 09:29:31 2014
@@ -295,6 +295,12 @@
 # define OS_NETBSD
 # define NO_VFORK
 # endif
+# ifdef __OpenBSD__
+# define unix
+# define OSMINOR "OS=OPENBSD"
+# define OS_OPENBSD
+# define NO_VFORK
+# endif
 # ifdef __QNX__
 # ifdef __QNXNTO__
 # define OSMINOR "OS=QNXNTO"
@@ -391,6 +397,7 @@
 
 # if !defined(OS_BSDI) && \
      !defined(OS_FREEBSD) && \
+     !defined(OS_OPENBSD) && \
      !defined(OS_NEXT) && \
      !defined(OS_MACHTEN) && \
      !defined(OS_MACOSX) && \
diff -up jam/pathunix.c jam_/pathunix.c
--- jam/pathunix.c	Sat Jan  4 06:14:02 2014
+++ jam_/pathunix.c	Sat Jan  4 09:32:06 2014
@@ -38,7 +38,7 @@
 
 # ifdef USE_PATHUNIX
 
-# if defined( OS_MACOSX )
+# if defined( OS_MACOSX ) || defined ( OS_OPENBSD )
 /* need unistd for the prototype for getcwd to avoid defaulting return to int on 64bit */
 /* XXX: others too ? */
 # include <unistd.h>