diff --git a/lemon/config.h.in b/lemon/config.h.in
new file mode 100644
--- /dev/null
+++ b/lemon/config.h.in
@@ -0,0 +1,5 @@
+/* Define to 1 if you have CPLEX. */
+#undef HAVE_CPLEX
+
+/* Define to 1 if you have GLPK. */
+#undef HAVE_GLPK