diff --git a/configure.ac b/configure.ac
index 4a88cd8..8951750 100644
--- a/configure.ac
+++ b/configure.ac
@@ -77,6 +77,7 @@
   if test "x$have_log4j" = "xyes" && test "x$have_hashcode" = "xyes" ; then
     ANT_FLAGS="$ANT_FLAGS -Dnoivy="
   fi
+  AC_SUBST(CLASSPATH)
   AC_SUBST(ANT_FLAGS)
 fi
 AM_CONDITIONAL([WITH_JAVA],