diff --git a/unittest/force-styles/tests/bond-harmonic_shift.yaml b/unittest/force-styles/tests/bond-harmonic_shift.yaml
index 7a41c2c3cd..61212a468b 100644
--- a/unittest/force-styles/tests/bond-harmonic_shift.yaml
+++ b/unittest/force-styles/tests/bond-harmonic_shift.yaml
@@ -17,7 +17,10 @@ bond_coeff: ! |
   4 650.0 1.2 0.2
   5 450.0 1.0 0.0
 equilibrium: 5 1.5 1.1 1.3 1.2 1
-extract: ! ""
+extract: ! |
+  k 1
+  r0 1
+  r1 1
 natoms: 29
 init_energy: -9395.519982389222
 init_stress: ! |-