diff --git a/callback.c b/callback.c
index 09a5e49b..6a888e89 100644
--- a/callback.c
+++ b/callback.c
@@ -65,7 +65,8 @@ void delete_callbacks_for_context(void *ctx)
 
     cbhead = newhead;
     cbtail = newtail;
-    newtail->next = NULL;
+    if (newtail)
+        newtail->next = NULL;
 }
 
 void queue_toplevel_callback(toplevel_callback_fn_t fn, void *ctx)