diff --git a/src/settings.cpp b/src/settings.cpp
index ab22e8ee6..19b8a72a5 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -408,10 +408,12 @@ void read_settings_xml()
 #endif
   }
 
+#ifdef _OPENMP
   if (dagmc) {
     warning("Forcing number of threads to 1 for DAGMC simulation.");
     omp_set_num_threads(1);
   }
+#endif
   
   // ==========================================================================
   // EXTERNAL SOURCE