diff --git a/Source/BoundaryConditions/MOSTAverage.cpp b/Source/BoundaryConditions/MOSTAverage.cpp
index b2a5f72e8..e2dfc0d99 100644
--- a/Source/BoundaryConditions/MOSTAverage.cpp
+++ b/Source/BoundaryConditions/MOSTAverage.cpp
@@ -270,7 +270,7 @@ MOSTAverage::set_k_indices_N()
             AMREX_ASSERT_WITH_MESSAGE(m_zref <= m_zhi - 0.5 * m_dz,
                                       "Query point must be below the last z-cell!");
 
-            int lk = static_cast<int>(floor((m_zref - m_zlo) / m_dz - 0.5));
+            int lk = static_cast<int>(floor((m_zref - m_zlo) / m_dz));
 
             m_zref = (lk + 0.5) * m_dz + m_zlo;