diff --git a/surface/src/3rdparty/opennurbs/opennurbs_lookup.cpp b/surface/src/3rdparty/opennurbs/opennurbs_lookup.cpp
index 49e52b4..a9578bd 100644
--- a/surface/src/3rdparty/opennurbs/opennurbs_lookup.cpp
+++ b/surface/src/3rdparty/opennurbs/opennurbs_lookup.cpp
@@ -666,6 +666,7 @@ std::size_t ON_SerialNumberMap::ActiveIdCount() const
   return m_active_id_count;
 }
 
+#pragma optimize("", off)
 struct ON_SerialNumberMap::SN_ELEMENT* ON_SerialNumberMap::FirstElement() const
 {
   struct SN_ELEMENT* e=0;
@@ -717,6 +718,7 @@ struct ON_SerialNumberMap::SN_ELEMENT* ON_SerialNumberMap::FirstElement() const
   }
   return e;
 }
+#pragma optimize("", on)
 
 struct ON_SerialNumberMap::SN_ELEMENT* ON_SerialNumberMap::LastElement() const
 {