diff --git a/src/test-gradient-method.cc b/src/test-gradient-method.cc
index bf4f9f560b9f5001c4180e1ef1fd42fa48a192b0..5ff673375849a0d5b1ed4ae97796da1c5f3602b3 100644
--- a/src/test-gradient-method.cc
+++ b/src/test-gradient-method.cc
@@ -152,7 +152,14 @@ void testTrivialFunction() {
   error -= returned;
   assert(error.two_norm() < 1e-10); // FIXME: 1e-10 sounds reasonable. Is it?
 
-  functionTester(J, start, 5);
+  double const ret1 = functionTester(J, start, 6);
+  std::cout << std::endl;
+
+  start[0] = 279;
+  start[1] = -96;
+
+  double const ret2 = functionTester(J, start, 16);
+  assert(std::abs(ret1 - ret2) < 1e-5);
 }
 
 int main() {