diff --git a/Include/pyport.h b/Include/pyport.h
index f71b9f4..2440c55 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -297,7 +297,7 @@
  *    This isn't reliable.  See Py_OVERFLOWED comments.
  *    X is evaluated more than once.
  */
-#if defined(__FreeBSD__) || defined(__OpenBSD__)
+#if defined(__FreeBSD__) || defined(__OpenBSD__) || (defined(__hpux) && defined(__ia64))
 #define _Py_SET_EDOM_FOR_NAN(X) if (isnan(X)) errno = EDOM;
 #else
 #define _Py_SET_EDOM_FOR_NAN(X) ;
diff --git a/Misc/NEWS b/Misc/NEWS
index 27483d4..33d6732 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@
 Core and builtins
 -----------------
 
+- Changes donated by Elemental Security to make it work on HP-UX 11 on
+  Itanium2 with HP's 64-bit compiler (SF patch #1225212).
+
 - Disallow keyword arguments for type constructors that don't use them
   (fixes bug #1119418).
 
diff --git a/Python/thread.c b/Python/thread.c
index 4c0edfb..5e7fc6c 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -45,6 +45,20 @@
 #define SUN_LWP
 #endif
 
+/* Check if we're running on HP-UX and _SC_THREADS is defined. If so, then
+   enough of the Posix threads package is implimented to support python 
+   threads.
+
+   This is valid for HP-UX 11.23 running on an ia64 system. If needed, add
+   a check of __ia64 to verify that we're running on a ia64 system instead
+   of a pa-risc system.
+*/
+#ifdef __hpux
+#ifdef _SC_THREADS
+#define _POSIX_THREADS
+#endif
+#endif
+
 #endif /* _POSIX_THREADS */
 
 
diff --git a/README b/README
index 07a38a0..df92b9f 100644
--- a/README
+++ b/README
@@ -368,7 +368,25 @@
 	compiler, some experience has shown that the compiler's
 	optimiser produces a completely broken version of python
 	(see http://www.python.org/sf/814976). To work around this,
-	edit the Makefile and remove -O from the OPT line.
+	edit the Makefile and remove -O from the OPT line.  (This is
+	old information; with the latest compiler this problem does
+	not occur.)
+
+	To build a 64-bit executable on an Itanium 2 system using HP's
+	compiler, use these environment variables:
+
+		CC=cc
+		CXX=aCC
+		BASECFLAGS="+DD64"
+		LDFLAGS="+DD64 -lxnet"
+
+	and call configure as:
+
+		./configure --without-gcc
+
+	then *unset* the environment variables again before running
+	make.  (At least one of these flags causes the build to fail
+	if it remains set.)
 
 HP PA-RISC 2.0: A recent bug report (http://www.python.org/sf/546117)
 	suggests that the C compiler in this 64-bit system has bugs