diff --git a/unittest/force-styles/tests/angle-fourier_simple.yaml b/unittest/force-styles/tests/angle-fourier_simple.yaml
index e1a394ee3a..bd72e67912 100644
--- a/unittest/force-styles/tests/angle-fourier_simple.yaml
+++ b/unittest/force-styles/tests/angle-fourier_simple.yaml
@@ -16,7 +16,10 @@ angle_coeff: ! |
   3  50.0  1.0 3.0
   4 100.0 -0.5 1.5
 equilibrium: 4 3.141592653589793 1.5707963267948966 1.0471975511965976 2.0943951023931953
-extract: ! ""
+extract: ! |
+  k 1
+  C 1
+  N 1
 natoms: 29
 init_energy: 2474.0748013590646
 init_stress: ! |-