1 files changed, 2 insertions, 0 deletions
diff --git a/c2.c b/c2.c
index de221c01d..f70dcb5a7 100644
--- a/c2.c
+++ b/c2.c
@@ -1292,6 +1292,8 @@ c2_match_once(session_t *ps, win *w, const c2_ptr_t cond) {
 bool
 c2_matchd(session_t *ps, win *w, const c2_lptr_t *condlst,
     const c2_lptr_t **cache, void **pdata) {
+  assert(IsViewable == w->a.map_state);
+
   // Check if the cached entry matches firstly
   if (cache && *cache && c2_match_once(ps, w, (*cache)->ptr)) {
     if (pdata)