diff --git a/tests/testGravityDerivatives.c b/tests/testGravityDerivatives.c
index 0a811cbda491c40f2f1db7bac5b1f3e2f7508b59..77240f397ee34753a05a6d18e8855bb226d7bb82 100644
--- a/tests/testGravityDerivatives.c
+++ b/tests/testGravityDerivatives.c
@@ -952,10 +952,13 @@ int main() {
     /* Compute distance */
     const double r2 = dx * dx + dy * dy + dz * dz;
     const double r_inv = 1. / sqrt(r2);
+    const double r = r2 * r_inv;
+    const double eps = r / 10.;
+    const double eps_inv = 1. / eps;
 
     /* Compute all derivatives */
     struct potential_derivatives_M2L pot;
-    compute_potential_derivatives_M2L(dx, dy, dz, r2, r_inv, 0., FLT_MAX, &pot);
+    compute_potential_derivatives_M2L(dx, dy, dz, r2, r_inv, eps, eps_inv, &pot);
 
     /* Minimal value we care about */
     const double min = 1e-9;