diff --git a/aclocal/ax_boost_base.m4 b/aclocal/ax_boost_base.m4
index 5894d0c..806f98b 100644
--- a/aclocal/ax_boost_base.m4
+++ b/aclocal/ax_boost_base.m4
@@ -37,7 +37,7 @@
 AC_DEFUN([AX_BOOST_BASE],
 [
 AC_ARG_WITH([boost],
-	AS_HELP_STRING([--with-boost@<:@=DIR@:>@], [use boost (default is yes) - it is possible to specify the root directory for boost (optional)]),
+	AS_HELP_STRING([--with-boost@<:@=DIR@:>@], [use boost [default=yes]. Optionally specify the root prefix dir where boost is installed]),
 	[
     if test "$withval" = "no"; then
 		want_boost="no"