diff --git a/benchmarks/moi_curvilinear.py b/benchmarks/moi_curvilinear.py
index d5a559f..6f8e1b1 100644
--- a/benchmarks/moi_curvilinear.py
+++ b/benchmarks/moi_curvilinear.py
@@ -65,8 +65,11 @@ def pset_execute_3d(self, interpolator, chunk, npart):
 
         lon = np.linspace(-10, 10, npart)
         lat = np.linspace(-30, -20, npart)
+        z = np.ones(npart) * 10  # 10 m depth
 
-        pset = parcels.ParticleSet(fieldset=fieldset, pclass=pclass, lon=lon, lat=lat)
+        pset = parcels.ParticleSet(
+            fieldset=fieldset, pclass=pclass, lon=lon, lat=lat, z=z
+        )
 
         pset.execute(
             parcels.kernels.AdvectionEE, runtime=runtime, dt=dt, verbose_progress=False