diff --git a/Misc/NEWS b/Misc/NEWS
index f42c8ec..06450ba 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -101,6 +101,8 @@
 Build
 -----
 
+- Define _BSD_SOURCE, to get access to POSIX extensions on OpenBSD 4.1+.
+
 - Patch #1673122: Use an explicit path to libtool when building a framework. 
   This avoids picking up GNU libtool from a users PATH.
 
diff --git a/configure b/configure
index 70e0e68..fe07570 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 52844 .
+# From configure.in Revision: 54284 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.59 for python 2.5.
 #
@@ -1388,6 +1388,14 @@
 _ACEOF
 
 
+# OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
+# also defined. This can be overridden by defining _BSD_SOURCE
+
+cat >>confdefs.h <<\_ACEOF
+#define _BSD_SOURCE 1
+_ACEOF
+
+
 # The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
 # u_int on Irix 5.3. Defining _BSD_TYPES brings it back.
 
diff --git a/configure.in b/configure.in
index 16d6ff1..b9cda94 100644
--- a/configure.in
+++ b/configure.in
@@ -50,6 +50,10 @@
 # them.
 AC_DEFINE(__BSD_VISIBLE, 1, [Define on FreeBSD to activate all library features])
 
+# OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
+# also defined. This can be overridden by defining _BSD_SOURCE
+AC_DEFINE(_BSD_SOURCE, 1, [Define on OpenBSD to activate all library features])
+
 # The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
 # u_int on Irix 5.3. Defining _BSD_TYPES brings it back.
 AC_DEFINE(_BSD_TYPES, 1, [Define on Irix to enable u_int])
diff --git a/pyconfig.h.in b/pyconfig.h.in
index 8448439..44e4881 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -909,6 +909,9 @@
 # undef _ALL_SOURCE
 #endif
 
+/* Define on OpenBSD to activate all library features */
+#undef _BSD_SOURCE
+
 /* Define on Irix to enable u_int */
 #undef _BSD_TYPES