diff --git a/src/subtype.c b/src/subtype.c
index 363599f1724ae..39ec6da875c37 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -1138,6 +1138,7 @@ static int forall_exists_subtype(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, in
         int set = e->Lunions.more;
         if (!sub || !set)
             break;
+        free(se.buf);
         save_env(e, &saved, &se);
         for (int i = set; i <= lastset; i++)
             statestack_set(&e->Lunions, i, 0);