diff --git a/aclocal.m4 b/aclocal.m4
index 64a311f40..76ddc0296 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -14,7 +14,7 @@
 AC_DEFUN([AX_CPP_IDENT],
 [AC_CACHE_CHECK([for ident support in C compiler], ax_cv_cpp_ident,
 [AC_TRY_COMPILE([
-#ident "$Id: aclocal.m4,v 1.6 2004/10/04 01:10:52 steve Exp $"
+#ident "$Id: aclocal.m4,v 1.7 2007/05/16 23:59:12 steve Exp $"
 ],[while (0) {}],
 [AS_VAR_SET(ax_cv_cpp_ident, yes)],
 [AS_VAR_SET(ax_cv_cpp_ident, no)])])
@@ -48,7 +48,7 @@ AC_DEFUN([AX_C_UNDERSCORES_LEADING],
 [AS_VAR_SET(ax_cv_c_underscores_leading, yes)],
 [AS_VAR_SET(ax_cv_c_underscores_leading, no)])])
 if test $ax_cv_c_underscores_leading = yes -a "$CYGWIN" != "yes" -a "$MINGW32" != "yes"; then
- AC_DEFINE(NEED_LU)
+ AC_DEFINE([NEED_LU], [1], [Symbol names in object files produced by C compiler have leading underscores.])
 fi
 ])# AX_C_UNDERSCORES_LEADING
 
@@ -63,7 +63,7 @@ AC_DEFUN([AX_C_UNDERSCORES_TRAILING],
 [AS_VAR_SET(ax_cv_c_underscores_trailing, yes)],
 [AS_VAR_SET(ax_cv_c_underscores_trailing, no)])])
 if test $ax_cv_c_underscores_trailing = yes; then
- AC_DEFINE(NEED_TU)
+ AC_DEFINE([NEED_TU], [1], [Symbol names in object files produced by C compiler have trailing underscores.])
 fi
 ])# AX_C_UNDERSCORES_TRAILING
 
diff --git a/configure.in b/configure.in
index 6f97c470f..f8a7dd7ff 100644
--- a/configure.in
+++ b/configure.in
@@ -66,7 +66,7 @@ AC_TRY_LINK(
 #include <sys/times.h>
 ,{clock_t a = times(0)/sysconf(_SC_CLK_TCK);},
 do_times=yes
-AC_DEFINE(HAVE_TIMES,1),
+AC_DEFINE([HAVE_TIMES], [1], [The times system call is available in the host operating system.]),
 do_times=no
 )
 AC_MSG_RESULT($do_times)
diff --git a/tgt-vvp/configure.in b/tgt-vvp/configure.in
index 7c3a26333..62e06d9f1 100644
--- a/tgt-vvp/configure.in
+++ b/tgt-vvp/configure.in
@@ -21,8 +21,8 @@ AX_CPP_PRECOMP
 # Do some more operating system specific setup.
 case "${host}" in
     *-*-linux*)
-	AC_DEFINE(_LARGEFILE_SOURCE)
-	AC_DEFINE(_LARGEFILE64_SOURCE)
+	AC_DEFINE([_LARGEFILE_SOURCE], [1], [Indicates LFS (i.e. the ability to create files larger than 2 GiB on 32-bit operating systems).])
+	AC_DEFINE([_LARGEFILE64_SOURCE], [1], [Indicates LFS (i.e. the ability to create files larger than 2 GiB on 32-bit operating systems).])
 	;;
 esac
 
diff --git a/vpi/configure.in b/vpi/configure.in
index 868c4f822..edff1072f 100644
--- a/vpi/configure.in
+++ b/vpi/configure.in
@@ -67,7 +67,7 @@ AX_CPP_PRECOMP
 file64_support=''
 case "${host}" in
     *-*-linux*)
-	AC_DEFINE(_LARGEFILE_SOURCE)
+	AC_DEFINE([_LARGEFILE_SOURCE], [1], [Indicates LFS (i.e. the ability to create files larger than 2 GiB on 32-bit operating systems).])
 	file64_support='-D_LARGEFILE_SOURCE=1 -D_FILE_OFFSET_BITS=64'
 	;;
 esac
diff --git a/vvp/configure.in b/vvp/configure.in
index ca2062893..b092c8c67 100644
--- a/vvp/configure.in
+++ b/vvp/configure.in
@@ -81,7 +81,7 @@ AC_CHECK_FUNCS(lround)
 # Linux does not provide mem stats in rusage, use /proc/self/statm.
 
 AC_CHECK_HEADERS(sys/resource.h)
-case "${host}" in *linux*) AC_DEFINE(LINUX) ;; esac
+case "${host}" in *linux*) AC_DEFINE([LINUX], [1], [Host operating system is Linux.]) ;; esac
 
 # Linker option used when compiling the target
 AX_LD_RDYNAMIC