diff --git a/modules/mol/mm/tests/test_simulation.cc b/modules/mol/mm/tests/test_simulation.cc
index ba9c282d6ebc45240a8a57e1d4952e0de713505e..4e46c5fc5b2666aabd0a122eee45791536441dac 100644
--- a/modules/mol/mm/tests/test_simulation.cc
+++ b/modules/mol/mm/tests/test_simulation.cc
@@ -173,9 +173,13 @@ BOOST_AUTO_TEST_CASE(test_simulation_energy_calculations){
   //Gromacs writes down the positions using nm instead of A, but
   //also has a precision of 3 digits.
 
-  BOOST_CHECK_CLOSE(sim.GetPotentialEnergy(), -2381.24, Real(1e-3));
+  // Threshold is relatively permissive (1e-1->0.1% difference) depending on
+  // OpenMM version / Hardware you might get slightly different results. 
+  // Error propagates when performing 200 steps steepest descent (minimizes from
+  // roughly 1981 down to -2381).
+  BOOST_CHECK_CLOSE(sim.GetPotentialEnergy(), -2381.24, Real(1e-1));
 }
 
 
 
-BOOST_AUTO_TEST_SUITE_END();
\ No newline at end of file
+BOOST_AUTO_TEST_SUITE_END();