diff --git a/examples/md.py b/examples/md.py
index d06d664b4de5bea7772c3e289468a73c54dd0c78..32bc1da44d44e6f1e3027979090ce511aa052f02 100644
--- a/examples/md.py
+++ b/examples/md.py
@@ -48,8 +48,8 @@ psim.add_property('mass', pairs.real(), 1.0)
 psim.add_property('linear_velocity', pairs.vector())
 psim.add_property('force', pairs.vector(), volatile=True)
 psim.add_feature('type', ntypes)
-psim.add_feature_property('type', 'epsilon', pairs.real(), [sigma for i in range(ntypes * ntypes)])
-psim.add_feature_property('type', 'sigma6', pairs.real(), [epsilon for i in range(ntypes * ntypes)])
+psim.add_feature_property('type', 'epsilon', pairs.real(), [epsilon for i in range(ntypes * ntypes)])
+psim.add_feature_property('type', 'sigma6', pairs.real(), [sigma6 for i in range(ntypes * ntypes)])
 
 psim.copper_fcc_lattice(nx, ny, nz, rho, temp, ntypes)
 #psim.set_domain_partitioner(pairs.block_forest())