diff --git a/modules/mol/mm/tests/test_topology.cc b/modules/mol/mm/tests/test_topology.cc
index d10bd05e6427ab64da9b54adb2fd076dd05370d6..5d8644fa25cd5b90f79a3c29acc3445e9ad0deb3 100644
--- a/modules/mol/mm/tests/test_topology.cc
+++ b/modules/mol/mm/tests/test_topology.cc
@@ -560,7 +560,7 @@ BOOST_AUTO_TEST_CASE(test_topology_merge){
   geom::Vec3 v0;
 
   top_eight->GetHarmonicBondParameters(harmonic_bond_indices[0],ui0,ui1,r0,r1);
-  BOOST_CHECK(r0 = 42.0 && r1 == 42000.0);
+  BOOST_CHECK(r0 == 42.0 && r1 == 42000.0);
 
   top_eight->GetHarmonicAngleParameters(harmonic_angle_indices[0],ui0,ui1,ui2,r0,r1);
   BOOST_CHECK(r0 == 24.0 && r1 == 24000.0);