diff --git a/libguile/tags.h b/libguile/tags.h
index 0d340c4b8..9bf780f3e 100644
--- a/libguile/tags.h
+++ b/libguile/tags.h
@@ -446,7 +446,9 @@ typedef unsigned long scm_t_bits;
 #define scm_tc7_cvect		53
 #define scm_tc7_svect		55
 #define scm_tc7_bvect		71
+#if 0
 #define scm_tc7_byvect		77
+#endif
 #define scm_tc7_ivect		79
 #endif