+#if defined (SCM_MAJOR_VERSION) && (SCM_MAJOR_VERSION > 1)
+#define GUILEV2 1
+#endif
+// TODO - remove GUILE1 definition when support for Guile 1 is dropped.
+#if defined (SCM_MAJOR_VERSION) && (SCM_MAJOR_VERSION < 2)
+#define GUILEV1 1
+#define GUILEV2 0
+#endif