1 files changed, 2 insertions, 0 deletions
diff --git a/src/common.cc b/src/common.cc
index 5e84c01..12fe710 100644
--- a/src/common.cc
+++ b/src/common.cc
@@ -103,6 +103,8 @@ struct Link {
 static inline void link_after(Link* prev, Link* nlink) {
   assert_neq(prev, nullptr);
   assert_neq(nlink, nullptr);
+  assert_neq(prev, nlink);
+  assert(nlink->prev == nullptr && nlink->next == nullptr);
 
   Link* next = prev->next;