--- a/nping/configure.ac
+++ b/nping/configure.ac
@@ -78,6 +78,7 @@
 
 # Remember that all following tests will run with this CXXFLAGS by default
 AC_MSG_CHECKING(for __func__)
+AH_TEMPLATE(__func__, [C99-specified function identifier])
 AC_TRY_COMPILE([
 #include <stdio.h>
 ],[printf ("%s", __func__);],
@@ -172,7 +173,7 @@
 
 OPENSSL_LIBS=
 if test "$use_openssl" = "yes"; then
-  AC_DEFINE(HAVE_OPENSSL)
+  AC_DEFINE(HAVE_OPENSSL, 1, [Have OpenSSL library])
   OPENSSL_LIBS="-lssl -lcrypto"
   LIBS_TMP="$LIBS"
   LIBS="$OPENSSL_LIBS $LIBS"
@@ -251,7 +252,7 @@
   PCAP_CLEAN="clean-pcap"
   PCAP_DIST_CLEAN="distclean-pcap"
 else
-  AC_DEFINE(HAVE_LIBPCAP)
+  AC_DEFINE(HAVE_LIBPCAP, 1, [Have libpcap library])
   LIBPCAP_LIBS="-lpcap"
   PCAP_DEPENDS=""
   PCAP_BUILD=""
@@ -333,7 +334,7 @@
         ac_cv_sockaddr_has_sa_len=yes,
         ac_cv_sockaddr_has_sa_len=no))
 if test $ac_cv_sockaddr_has_sa_len = yes ; then
-        AC_DEFINE(HAVE_SOCKADDR_SA_LEN)
+        AC_DEFINE(HAVE_SOCKADDR_SA_LEN, 1, [struct sockaddr has sa_len member])
 fi
 
 
@@ -350,7 +351,7 @@
         ac_cv_sockaddr_in_has_sin_len=yes,
         ac_cv_sockaddr_in_has_sin_len=no))
 if test $ac_cv_sockaddr_in_has_sin_len = yes ; then
-        AC_DEFINE(HAVE_SOCKADDR_IN_SIN_LEN)
+        AC_DEFINE(HAVE_SOCKADDR_IN_SIN_LEN, 1, [struct sockaddr_in has sin_len member])
 fi
 
 
@@ -367,7 +368,7 @@
         ac_cv_sockaddr_in6_has_sin6_len=yes,
         ac_cv_sockaddr_in6_has_sin6_len=no))
 if test $ac_cv_sockaddr_in6_has_sin6_len = yes ; then
-        AC_DEFINE(HAVE_SOCKADDR_IN6_SIN6_LEN)
+        AC_DEFINE(HAVE_SOCKADDR_IN6_SIN6_LEN, 1, [struct sockaddr_in6 has sin6_len member])
 fi
 
 
@@ -375,6 +376,7 @@
 AC_C_BIGENDIAN
 
 AC_MSG_CHECKING([if struct in_addr is a wacky huge structure (some Sun boxes)])
+AH_TEMPLATE(IN_ADDR_DEEPSTRUCT, [], [struct in_addr is a wacky huge structure (some Sun boxes)])
 
 AC_TRY_COMPILE([#include <netinet/in.h>], struct in_addr i; i._S_un._S_addr;, \
              AC_DEFINE(IN_ADDR_DEEPSTRUCT) \
@@ -435,7 +437,7 @@
         ac_cv_ip_has_ip_sum=yes,
         ac_cv_ip_has_ip_sum=no))
 if test $ac_cv_ip_has_ip_sum = yes ; then
-        AC_DEFINE(HAVE_IP_IP_SUM)
+        AC_DEFINE(HAVE_IP_IP_SUM, 1, [struct ip has ip_sum member])
 fi
 
 AC_CACHE_CHECK(if function signal is accessible, ac_cv_have_signal,
@@ -456,33 +458,36 @@
         ac_cv_have_signal=yes,
         ac_cv_have_signal=no))
 if test $ac_cv_have_signal = yes ; then
-        AC_DEFINE(HAVE_SIGNAL)
+        AC_DEFINE(HAVE_SIGNAL, 1, [ssignal function is accessible])
 fi
 
 
 
 
+AH_TEMPLATE(SOLARIS, [Sun/Oracle Solaris])
+AH_TEMPLATE(STUPID_SOLARIS_CHECKSUM_BUG, [],
+            [A bug in Solaris causing incorrect IP checksums])
 case "$host" in
   *alpha-dec-osf*)
-    AC_DEFINE(DEC)
+    AC_DEFINE(DEC, 1, [DEC Alpha])
     ;;
   *-netbsd* | *-knetbsd*-gnu)
-    AC_DEFINE(NETBSD)
+    AC_DEFINE(NETBSD, 1, [NetBSD])
     ;;
   *-openbsd*)
-    AC_DEFINE(OPENBSD)
+    AC_DEFINE(OPENBSD, 1, [OpenBSD])
     ;;
   *-freebsd* | *-kfreebsd*-gnu | *-dragonfly*)
-    AC_DEFINE(FREEBSD)
+    AC_DEFINE(FREEBSD, 1, [FreeBSD])
     ;;
   *-bsdi*)
-    AC_DEFINE(BSDI)
+    AC_DEFINE(BSDI, 1, [BSD/OS])
     ;;
   *-sgi-irix5* | *-sgi-irix6*)
-    AC_DEFINE(IRIX)
+    AC_DEFINE(IRIX, 1, [IRIX])
     ;;
   *-hpux*)
-    AC_DEFINE(HPUX)
+    AC_DEFINE(HPUX, 1, [HP-UX])
     # To link with libnet and NM (/usr/lib/libnm.sl) library
     # on HP-UX 11.11 (other versions?) Mikhail Zakharov (zmey20000 () yahoo com)
     AC_CHECK_LIB(nm, open_mib)
@@ -524,14 +529,15 @@
     AC_DEFINE(SOLARIS)
     ;;
   *-sunos4*)
-    AC_DEFINE(SUNOS)
-    AC_DEFINE(SPRINTF_RETURNS_STRING)
+    AC_DEFINE(SUNOS, 1, [SunOS 4])
+    AC_DEFINE(SPRINTF_RETURNS_STRING, 1,
+              [sprintf(9f) returns its first argument, not the number of characters printed])
     ;;
   *-linux*)
-    AC_DEFINE(LINUX)
+    AC_DEFINE(LINUX, 1, [Linux])
     ;;
   *-apple-darwin*)
-    AC_DEFINE(MACOSX)
+    AC_DEFINE(MACOSX, 1, [Apple OS X])
     dnl on Mac OSX the math library seems to contain unwanted getopt cruft
     AC_CHECK_LIB(m, main)
     needs_cpp_precomp=yes
--- a/nbase/acinclude.m4
+++ b/nbase/acinclude.m4
@@ -137,7 +137,7 @@
 
 if test "$ac_cv_define_sockaddr_in6" = "yes"; then
   have_sockaddr_in6=1
-  AC_DEFINE(HAVE_SOCKADDR_IN6)
+  AC_DEFINE(HAVE_SOCKADDR_IN6, 1, [Define if struct sockaddr_in6 exists])
 else
   have_sockaddr_in6=0
 fi
@@ -166,7 +166,7 @@
 
 if test "$ac_cv_define_af_inet6" = "yes"; then
   have_af_inet6=1
-  AC_DEFINE(HAVE_AF_INET6)
+  AC_DEFINE(HAVE_AF_INET6, 1, [Define if AF_INET6 is defined])
 else
   have_af_inet6=0
 fi
@@ -195,7 +195,7 @@
 
 if test "$ac_cv_define_sockaddr_storage" = "yes"; then
   have_sockaddr_storage=1
-  AC_DEFINE(HAVE_SOCKADDR_STORAGE)
+  AC_DEFINE(HAVE_SOCKADDR_STORAGE, 1, [Define if struct sockaddr_storage exists])
 else
   have_sockaddr_storage=0
 fi
--- a/nbase/configure.ac
+++ b/nbase/configure.ac
@@ -129,7 +129,7 @@
         ac_cv_sockaddr_has_sa_len=yes,
         ac_cv_sockaddr_has_sa_len=no))
 if test $ac_cv_sockaddr_has_sa_len = yes ; then
-        AC_DEFINE(HAVE_SOCKADDR_SA_LEN)
+        AC_DEFINE(HAVE_SOCKADDR_SA_LEN, 1, [define if sockaddr has sa_len member])
 fi
 
 dnl check endedness
@@ -225,7 +225,7 @@
 fi
 
 if test "$have_ipv6" = "1"; then
-  AC_DEFINE(HAVE_IPV6)
+  AC_DEFINE(HAVE_IPV6, 1, [define if IPv6 is available])
 fi
 
 # First we test whether they specified openssl desires explicitly
@@ -286,7 +286,7 @@
 fi
 
 if test "$use_openssl" = "yes"; then
-  AC_DEFINE(HAVE_OPENSSL)
+  AC_DEFINE(HAVE_OPENSSL, 1, [define if libssl is available])
 fi
 
 CHECK_PROC_SELF_EXE
--- a/ncat/configure.ac
+++ b/ncat/configure.ac
@@ -176,7 +176,7 @@
   PCAP_BUILD=""
   PCAP_CLEAN=""
   PCAP_DIST_CLEAN=""
-  AC_DEFINE(HAVE_LIBPCAP)
+  AC_DEFINE([HAVE_LIBPCAP], [1], [Define to 1 if you have libpcap])
 else
   if test "${LIBPCAP_INC+set}" = "set"; then
     LDFLAGS="-L$libpcapdir $_ldflags"
@@ -286,7 +286,7 @@
     LUA_BUILD="build-lua"
     LUA_CLEAN="clean-lua"
     LUA_DIST_CLEAN="distclean-lua"
-    AC_DEFINE(LUA_INCLUDED)
+    AC_DEFINE([LUA_INCLUDED], [1], [Define to 1 if you have LUA])
   else
     AC_MSG_RESULT(yes) 
   fi
--- a/nsock/src/configure.ac
+++ b/nsock/src/configure.ac
@@ -24,15 +24,18 @@
 dnl Host specific hacks
 AC_CANONICAL_HOST
 
+AH_TEMPLATE(SOLARIS, [Sun/Oracle Solaris])
+AH_TEMPLATE(IRIX, [IRIX])
+
 case "$host" in
   *alpha-dec-osf*)
-    AC_DEFINE(DEC)
+    AC_DEFINE(DEC, 1, [DEC Alpha])
     ;;
   *-netbsd* | *-knetbsd*-gnu)
-    AC_DEFINE(NETBSD)
+    AC_DEFINE(NETBSD, 1, [NetBSD])
     ;;
   *-openbsd*)
-    AC_DEFINE(OPENBSD)
+    AC_DEFINE(OPENBSD, 1, [OpenBSD])
     ;;
   *-sgi-irix5*)
     AC_DEFINE(IRIX)
@@ -41,12 +44,12 @@
     AC_DEFINE(IRIX)
     ;;
   *-hpux*)
-    AC_DEFINE(HPUX)
+    AC_DEFINE(HPUX, 1, [HP-UX])
     ;;
   *-solaris2.1[[1-9]]*)
     AC_DEFINE(SOLARIS)
     # Solaris 11 and later use BPF packet capture rather than DLPI.
-    AC_DEFINE(SOLARIS_BPF_PCAP_CAPTURE)
+    AC_DEFINE(SOLARIS_BPF_PCAP_CAPTURE, 1, [BPF packet capture on Solaris])
     ;;
   *-solaris2.0*)  
     AC_DEFINE(SOLARIS)
@@ -73,19 +76,19 @@
     AC_DEFINE(SOLARIS)
     ;;
   *-sunos4*)
-    AC_DEFINE(SUNOS)
+    AC_DEFINE(SUNOS, 1, [SunOS 4])
     ;;
   *-linux*)
-    AC_DEFINE(LINUX)
+    AC_DEFINE(LINUX, 1, [Linux])
     ;;
   *-freebsd* | *-kfreebsd*-gnu | *-dragonfly*)
-    AC_DEFINE(FREEBSD)
+    AC_DEFINE(FREEBSD, 1, [FreeBSD])
     ;;
   *-bsdi*)
-    AC_DEFINE(BSDI)
+    AC_DEFINE(BSDI, 1, [BSD/OS])
     ;;
   *-apple-darwin*)
-    AC_DEFINE(MACOSX)
+    AC_DEFINE(MACOSX, 1, [Apple OS X])
     ;;
 esac
 
@@ -160,7 +163,7 @@
   have_libpcap=yes
 fi
 if test "$have_libpcap" != "no"; then
-  AC_DEFINE(HAVE_PCAP)
+  AC_DEFINE(HAVE_PCAP, 1, [libpcap is available])
   if test "${LIBPCAP_INC+set}" = "set"; then
     CPPFLAGS="-I$LIBPCAP_INC $CPPFLAGS"
     LDFLAGS="-L$LIBPCAP_LIB $LDFLAGS"
@@ -170,8 +173,8 @@
 
 PCAP_DEFINE_NETMASK_UNKNOWN
 
-AX_HAVE_EPOLL([AC_DEFINE(HAVE_EPOLL)], )
-AX_HAVE_POLL([AC_DEFINE(HAVE_POLL)], )
+AX_HAVE_EPOLL([AC_DEFINE(HAVE_EPOLL, 1, [epoll is available])], )
+AX_HAVE_POLL([AC_DEFINE(HAVE_POLL, 1, [poll is available])], )
 AC_CHECK_FUNCS(kqueue kevent, [AC_DEFINE(HAVE_KQUEUE)], )
 
 dnl Checks for programs.
@@ -255,21 +258,21 @@
 
 OPENSSL_LIBS=
 if test "$use_openssl" = "yes"; then
-  AC_DEFINE(HAVE_OPENSSL)
+  AC_DEFINE(HAVE_OPENSSL, 1, [openssl is available])
   OPENSSL_LIBS="-lssl -lcrypto"
   LIBS_TMP="$LIBS"
   LIBS="$OPENSSL_LIBS $LIBS"
   AC_MSG_CHECKING([for SSL_set_tlsext_host_name])
   AC_TRY_LINK([#include <openssl/ssl.h>], [SSL_set_tlsext_host_name(NULL, NULL)],
-    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_SSL_SET_TLSEXT_HOST_NAME)],
+    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_SSL_SET_TLSEXT_HOST_NAME, 1, [SSL_set_tlsext_host_name available])],
     [AC_MSG_RESULT([no])])
   AC_MSG_CHECKING([for DTLS_client_method])
   AC_TRY_LINK([#include <openssl/ssl.h>], [DTLS_client_method()],
-    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_DTLS_CLIENT_METHOD)],
+    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_DTLS_CLIENT_METHOD, 1, [DTLS_client_method available])],
     [AC_MSG_RESULT([no])])
   AC_MSG_CHECKING([for SSL_set_alpn_protos])
   AC_TRY_LINK([#include <openssl/ssl.h>], [SSL_set_alpn_protos(NULL, NULL, 0)],
-    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_ALPN_SUPPORT)],
+    [AC_MSG_RESULT([yes]); AC_DEFINE(HAVE_ALPN_SUPPORT, 1, [SSL ALPN protos support])],
     [AC_MSG_RESULT([no])])
   LIBS="$LIBS_TMP"