diff --git a/src/settings.cpp b/src/settings.cpp
index 04facb2f4..ab22e8ee6 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -408,6 +408,11 @@ void read_settings_xml()
 #endif
   }
 
+  if (dagmc) {
+    warning("Forcing number of threads to 1 for DAGMC simulation.");
+    omp_set_num_threads(1);
+  }
+  
   // ==========================================================================
   // EXTERNAL SOURCE