diff --git a/agen5/guile-iface.h b/agen5/guile-iface.h
index 0aeabb0..6ce3520 100644
--- a/agen5/guile-iface.h
+++ b/agen5/guile-iface.h
@@ -9,7 +9,7 @@
 # error AutoGen does not work with this version of Guile
   choke me.
 
-#elif GUILE_VERSION < 201000
+#else
 # define AG_SCM_IS_PROC(_p)           scm_is_true( scm_procedure_p(_p))
 # define AG_SCM_LIST_P(_l)            scm_is_true( scm_list_p(_l))
 # define AG_SCM_PAIR_P(_p)            scm_is_true( scm_pair_p(_p))
@@ -24,9 +24,6 @@
 # define AG_SCM_TO_ULONG(_v)          ((unsigned long)scm_to_ulong(_v))
 # define AG_SCM_VEC_P(_v)             scm_is_vector(_v)
 
-#else
-# error unknown GUILE_VERSION
-  choke me.
 #endif
 
 #endif /* MUTATING_GUILE_IFACE_H_GUARD */
