1 files changed, 1 insertions, 1 deletions

diff --git a/lib.c b/lib.c
index 97d0eece..08deb233 100644
--- a/lib.c
+++ b/lib.c
@@ -615,7 +615,7 @@ loc listref_l(val list, val ind)
 
 loc tail(val cons)
 {
-  while (cdr(cons))
+  while (consp(cdr(cons)))
     cons = cdr(cons);
   return cdr_l(cons);
 }