diff --git a/list.c b/list.c
index 7a0c33b..ed73710 100644
--- a/list.c
+++ b/list.c
@@ -29,7 +29,7 @@ List list_with_len(size_t element_size, size_t len) {
 
 List list_copy(const List* source) {
     List self = list_init(source->element_size);
-    list_set_len(&self, source->cap);
+    list_set_len(&self, source->len);
     if(self.cap > 0) {
         memcpy(self.data, source->data, source->element_size * source->len);
     } else {