diff --git a/tests/test_elastica.py b/tests/test_elastica.py
index 49a6383..9ff0619 100644
--- a/tests/test_elastica.py
+++ b/tests/test_elastica.py
@@ -242,7 +242,7 @@ def energy(theta: npt.NDArray, B, theta_0, F) -> Array:
 
         residual = C.sub(C.codifferential(C.star(moment)), load)
 
-        return residual.coeffs[1:]
+        return residual.coeffs.flatten()[1:]
 
     energy_grad = energy