erts: GC needs the size even if the frag is not referenced

1 files changed, 1 insertions, 2 deletions

diff --git a/erts/emulator/beam/erl_map.c b/erts/emulator/beam/erl_map.c
index 4af8e6f274..5d965f3116 100644
--- a/erts/emulator/beam/erl_map.c
+++ b/erts/emulator/beam/erl_map.c
@@ -1008,6 +1008,7 @@ static Eterm flatmap_merge(Process *p, Eterm nodeA, Eterm nodeB) {
 
     n = n1 + n2 - unused_size;
     *thp = make_arityval(n);
+    mp_new->size = n;
 
     /* Reshape map to a hashmap if the map exceeds the limit */
 
@@ -1043,8 +1044,6 @@ static Eterm flatmap_merge(Process *p, Eterm nodeA, Eterm nodeB) {
 	return res;
     }
 
-    mp_new->size = n;
-
     return make_flatmap(mp_new);
 }