diff --git a/CHANGES b/CHANGES
index f65203e..6f35fce 100644
--- a/CHANGES
+++ b/CHANGES
@@ -107,6 +107,9 @@ porting:
 	compile errors when they were already provided by build framework.
 	Thanks to Liyu Liu for providing a patch.
 
+	David Arnstein contributed a patch for NetBSD 5.1 including stdbool.h
+	support and appropriate files in Config/
+
 testing:
 	Do not distribute testcert.conf with socat source but generate it
 	(and new testcert6.conf) during test.sh run.
diff --git a/Makefile.in b/Makefile.in
index 01f11f9..7d7771d 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -82,6 +82,7 @@ OSFILES = Config/Makefile.Linux-2-6-24 Config/config.Linux-2-6-24.h \
 	Config/Makefile.SunOS-5-10 Config/config.SunOS-5-10.h \
 	Config/Makefile.FreeBSD-6-1 Config/config.FreeBSD-6-1.h \
 	Config/Makefile.NetBSD-4-0 Config/config.NetBSD-4-0.h \
+	Config/Makefile.NetBSD-5-1 Config/config.NetBSD-5-1.h \
 	Config/Makefile.OpenBSD-4-3 Config/config.OpenBSD-4-3.h \
 	Config/Makefile.AIX-5-3 Config/config.AIX-5-3.h \
 	Config/Makefile.Cygwin-1-5-25 Config/config.Cygwin-1-5-25.h \
diff --git a/config.h.in b/config.h.in
index 3ed5bff..40ccf6a 100644
--- a/config.h.in
+++ b/config.h.in
@@ -146,6 +146,9 @@
 /* Define if you have the hstrerror prototype */
 #undef HAVE_PROTOTYPE_HSTRERROR
 
+/* Define if you have the <stdbool.h> header file.  */
+#undef HAVE_STDBOOL_H
+
 /* Define if you have the <inttypes.h> header file.  */
 #undef HAVE_INTTYPES_H
 
diff --git a/configure.in b/configure.in
index 52d0293..8d8fff6 100644
--- a/configure.in
+++ b/configure.in
@@ -57,6 +57,7 @@ export CFLAGS
 
 dnl Checks for header files.
 AC_HEADER_STDC
+AC_CHECK_HEADERS(stdbool.h)
 AC_CHECK_HEADERS(inttypes.h)
 AC_HEADER_SYS_WAIT
 AC_CHECK_HEADERS(fcntl.h limits.h strings.h sys/param.h sys/ioctl.h sys/time.h syslog.h unistd.h)
@@ -768,7 +769,10 @@ AC_CHECK_TYPE(sig_atomic_t,AC_DEFINE(HAVE_TYPE_SIG_ATOMIC_T),,[#include "sysincl
 
 AC_MSG_CHECKING(for bool)
 AC_CACHE_VAL(sc_cv_type_bool,
-[AC_TRY_COMPILE([],[bool b;],
+[AC_TRY_COMPILE([#ifdef HAVE_STDBOOL_H
+   #include <stdbool.h>
+   #endif],
+[bool b;],
 [sc_cv_type_bool=yes],
 [sc_cv_type_bool=no])])
 if test $sc_cv_type_bool = yes; then
diff --git a/dalan.c b/dalan.c
index 1d7334f..2bf4dd2 100644
--- a/dalan.c
+++ b/dalan.c
@@ -1,12 +1,16 @@
 /* source: dalan.c */
-/* Copyright Gerhard Rieger 2001-2008 */
+/* Copyright Gerhard Rieger */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* idea of a low level data description language. currently only a most
    primitive subset exists. */
 
+#include "config.h"
 #include <stdio.h>
 #include <stdlib.h>
+#if HAVE_STDBOOL_H
+#include <stdbool.h>
+#endif
 #include <ctype.h>
 #include "dalan.h"
 
diff --git a/sysincludes.h b/sysincludes.h
index 9635f12..094a118 100644
--- a/sysincludes.h
+++ b/sysincludes.h
@@ -5,6 +5,9 @@
 #ifndef __sysincludes_h_included
 #define __sysincludes_h_included 1
 
+#if HAVE_STDBOOL_H
+#include <stdbool.h>	/* bool, true, false */
+#endif
 #if HAVE_INTTYPES_H
 #include <inttypes.h>	/* uint16_t */
 #endif