diff --git a/unix/moduselect.c b/unix/moduselect.c
index 0d06cc5309092a89d5993148c0153ca75942a8aa..9abcc19dd738b6c4c0fa7c515ec2ac223e9414f2 100644
--- a/unix/moduselect.c
+++ b/unix/moduselect.c
@@ -65,7 +65,9 @@ STATIC mp_obj_t poll_register(uint n_args, const mp_obj_t *args) {
             }
         }
         if (entries->fd != -1) {
-            assert(0);
+            i = self->len++;
+            self->entries = m_renew(struct pollfd, self->entries, self->alloc, self->alloc + 4);
+            self->alloc += 4;
         }
     }