diff --git a/boehm-gc/ChangeLog b/boehm-gc/ChangeLog
index 81bf9f6112f1b8775e1091726c687f5aac0818d9..1195d7ee5e989547ad963d0ed83bc226f5e32758 100644
--- a/boehm-gc/ChangeLog
+++ b/boehm-gc/ChangeLog
@@ -1,3 +1,10 @@
+2006-03-24  Andreas Tobler  <a.tobler@schweiz.ch>
+	John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
+
+	* configure.ac (THREADS): Add REENTRANT for *-*-hpux11*.
+	Warn about POSIX threads not being supported for *-*-hpux10*.
+	* configure: Regenerate.
+
 2006-02-09  Tom Tromey  <tromey@redhat.com>
 
 	* pthread_support.c: Conditionally include dlfcn.h.
diff --git a/boehm-gc/configure b/boehm-gc/configure
index e0223dd7ea3cba3ee3ad2dcc555ff7a6d27460a3..65575a5d137dcbce6f537e2cd8e2cc38da567c65 100755
--- a/boehm-gc/configure
+++ b/boehm-gc/configure
@@ -5409,9 +5409,9 @@ _ACEOF
 _ACEOF
 
 	;;
-     *-*-hpux*)
-	{ echo "$as_me:$LINENO: WARNING: \"Only HP/UX 11 threads are supported.\"" >&5
-echo "$as_me: WARNING: \"Only HP/UX 11 threads are supported.\"" >&2;}
+     *-*-hpux11*)
+	{ echo "$as_me:$LINENO: WARNING: \"Only HP-UX 11 POSIX threads are supported.\"" >&5
+echo "$as_me: WARNING: \"Only HP-UX 11 POSIX threads are supported.\"" >&2;}
 
 cat >>confdefs.h <<\_ACEOF
 #define GC_HPUX_THREADS 1
@@ -5433,6 +5433,16 @@ _ACEOF
 _ACEOF
 
 	THREADLIBS="-lpthread -lrt"
+	# HPUX needs REENTRANT for the _r calls.
+
+cat >>confdefs.h <<\_ACEOF
+#define _REENTRANT 1
+_ACEOF
+
+	;;
+     *-*-hpux10*)
+	{ echo "$as_me:$LINENO: WARNING: \"Only HP-UX 11 POSIX threads are supported.\"" >&5
+echo "$as_me: WARNING: \"Only HP-UX 11 POSIX threads are supported.\"" >&2;}
 	;;
      *-*-freebsd*)
 	{ echo "$as_me:$LINENO: WARNING: \"FreeBSD does not yet fully support threads with Boehm GC.\"" >&5
diff --git a/boehm-gc/configure.ac b/boehm-gc/configure.ac
index 2b9663dec20c3bfa7ade0a21af6ca8b938b11934..69ad5cd3ab9666aadd8c83953fd835efc5397ebc 100644
--- a/boehm-gc/configure.ac
+++ b/boehm-gc/configure.ac
@@ -140,8 +140,8 @@ case "$THREADS" in
 	AC_DEFINE(GC_AIX_THREADS,1,[support AIX threads])
 	AC_DEFINE(_REENTRANT,1)
 	;;
-     *-*-hpux*)
-	AC_MSG_WARN("Only HP/UX 11 threads are supported.")
+     *-*-hpux11*)
+	AC_MSG_WARN("Only HP-UX 11 POSIX threads are supported.")
 	AC_DEFINE(GC_HPUX_THREADS,1,[enables support for HP/UX 11 pthreads])
 	AC_DEFINE(_POSIX_C_SOURCE,199506L,[POSIX version of C Source])
 	if test "${enable_parallel_mark}" = yes; then
@@ -149,6 +149,11 @@ case "$THREADS" in
 	fi
 	AC_DEFINE(THREAD_LOCAL_ALLOC,1)
 	THREADLIBS="-lpthread -lrt"
+	# HPUX needs REENTRANT for the _r calls.
+	AC_DEFINE(_REENTRANT, 1, [Required define if using POSIX threads])
+	;;
+     *-*-hpux10*)
+	AC_MSG_WARN("Only HP-UX 11 POSIX threads are supported.")
 	;;
      *-*-freebsd*)
 	AC_MSG_WARN("FreeBSD does not yet fully support threads with Boehm GC.")