diff --git a/src/subtype.c b/src/subtype.c
index fcb4aac2aaef2..e05965caa0ee7 100644
--- a/src/subtype.c
+++ b/src/subtype.c
@@ -1170,7 +1170,7 @@ static int subtype(jl_value_t *x, jl_value_t *y, jl_stenv_t *e, int param)
         x = pick_union_element(x, e, 0);
     }
     if (jl_is_uniontype(y)) {
-        if (x == ((jl_uniontype_t*)y)->a || x == ((jl_uniontype_t*)y)->b)
+        if (in_union(y, x))
             return 1;
         if (jl_is_unionall(x))
             return subtype_unionall(y, (jl_unionall_t*)x, e, 0, param);