diff --git a/src/iqbal.c b/src/iqbal.c
index ddbd4a7..f4c29c6 100644
--- a/src/iqbal.c
+++ b/src/iqbal.c
@@ -249,7 +249,7 @@ _iqbal_objfn_value(struct _iqbal_state *state, float x[2])
 static void
 _iqbal_objfn_gradient(struct _iqbal_state *state, float x[2], float v, float grad[2])
 {
-	const float GRAD_STEP = 0.001f;
+	const float GRAD_STEP = 1e-6f;
 	float xd[2], vd[2];
 
 	xd[0] = x[0] + GRAD_STEP; xd[1] = x[1];