diff --git a/unittest/force-styles/tests/improper-cossq.yaml b/unittest/force-styles/tests/improper-cossq.yaml
index 4faaa2214a..567e45da55 100644
--- a/unittest/force-styles/tests/improper-cossq.yaml
+++ b/unittest/force-styles/tests/improper-cossq.yaml
@@ -13,7 +13,9 @@ improper_style: cossq
 improper_coeff: ! |
   1  75.0 120.2
   2  45.0  59.5
-extract: ! ""
+extract: ! |
+  k 1
+  chi 1
 natoms: 29
 init_energy: 47.901206451962224
 init_stress: ! |-