diff --git a/unittest/force-styles/tests/angle-fourier.yaml b/unittest/force-styles/tests/angle-fourier.yaml
index 61165c5a92..275d62beca 100644
--- a/unittest/force-styles/tests/angle-fourier.yaml
+++ b/unittest/force-styles/tests/angle-fourier.yaml
@@ -16,7 +16,11 @@ angle_coeff: ! |
   3  50.0 0.0 0.0 1.0
   4 100.0 0.3 0.3 0.3
 equilibrium: 4 3.141592653589793 1.5707963267948966 1.5707963267948966 1.8234765819369754
-extract: ! ""
+extract: ! |
+  k 1
+  C0 1
+  C1 1
+  C2 1
 natoms: 29
 init_energy: 400.84036632010225
 init_stress: ! |-