diff --git a/CHANGES b/CHANGES
index c9a34891e..42f577bcb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,9 @@
 
                                   Changelog
 
+Daniel Stenberg (23 Sep 2009)
+- HPUX does need _REENTRANT too to build really thread-safe.
+
 Daniel Stenberg (16 Sep 2009)
 - Sven Anders reported that we introduced a cert verfication flaw for OpenSSL-
   powered libcurl in 7.19.6. If there was a X509v3 Subject Alternative Name
diff --git a/m4/curl-reentrant.m4 b/m4/curl-reentrant.m4
index 9b6c9663f..9ce251584 100644
--- a/m4/curl-reentrant.m4
+++ b/m4/curl-reentrant.m4
@@ -5,7 +5,7 @@
 #                            | (__| |_| |  _ <| |___
 #                             \___|\___/|_| \_\_____|
 #
-# Copyright (C) 1998 - 2008, Daniel Stenberg, <daniel@haxx.se>, et al.
+# Copyright (C) 1998 - 2009, Daniel Stenberg, <daniel@haxx.se>, et al.
 #
 # This software is licensed as described in the file COPYING, which
 # you should have received as part of this distribution. The terms
@@ -377,7 +377,7 @@ dnl Internal macro for CURL_CONFIGURE_REENTRANT.
 
 AC_DEFUN([CURL_CHECK_NEED_REENTRANT_SYSTEM], [
   case $host in
-    *-*-solaris*)
+    *-*-solaris* | *-*-hpux*)
       tmp_need_reentrant="yes"
       ;;
     *)