--- a/configure.in
+++ b/configure.in
@@ -20,7 +20,7 @@
 ### along with Octave; see the file COPYING.  If not, write to the Free
 ### Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 
-AC_REVISION($Revision: 1.122 $)
+AC_REVISION($Revision: 1.123 $)
 AC_PREREQ(2.0)
 AC_INIT(src/octave.cc)
 AC_CONFIG_HEADER(config.h)
@@ -96,6 +96,23 @@
 AC_SUBST(LIBINFO)
 AC_SUBST(INFO_DIR)
 
+### Allow the user disable support for plplot.
+
+PLPLOT_DIR=plplot
+USE_PLPLOT=true
+LIBPLPLOT=../plplot/libplplot.a
+AC_ARG_ENABLE(plplot,
+  [  --enable-plplot         use plplot for plotting (default is yes)],
+  [if test $enableval = no; then
+     USE_PLPLOT=false;
+     LIBPLPLOT="";
+     PLPLOT_DIR="";
+   fi], [])
+if $USE_PLPLOT; then
+  AC_DEFINE(USE_PLPLOT, 1)
+fi
+AC_SUBST(LIBPLPLOT)
+AC_SUBST(PLPLOT_DIR)
 
 ### Allow the user disable support for command line editing using GNU
 ### readline.
@@ -786,7 +803,7 @@
 
 ### Run configure in subdirectories.
 
-AC_CONFIG_SUBDIRS(kpathsea libcruft scripts $INFO_DIR)
+AC_CONFIG_SUBDIRS(kpathsea libcruft scripts $INFO_DIR $PLPLOT_DIR)
 
 ### Do the substitutions in all the Makefiles.