diff --git a/src/list.c b/src/list.c
index 3d66ce7..25ace15 100644
--- a/src/list.c
+++ b/src/list.c
@@ -281,6 +281,7 @@ list_length (List list)
 {
   int n;
 
+  n = 0;
   while (list != NULL)
     {
       n++;