diff --git a/b2/subex.c b/b2/subex.c
index 9542632..db851e1 100644
--- a/b2/subex.c
+++ b/b2/subex.c
@@ -104,9 +104,9 @@ static char *compose(const struct chunk *c,
 			append(&res, &res_len, c->u.s);
 			break;
 		case ct_var:
-			val = var_lookup(in, c->u.var);
+			val = var_lookup(out, c->u.var);
 			if (!val)
-				val = var_lookup(out, c->u.var);
+				val = var_lookup(in, c->u.var);
 			assert(val);
 			append(&res, &res_len, val);
 			break;