diff --git a/src/FDM/LaRCsim.cxx b/src/FDM/LaRCsim.cxx
index d290b45d6..309840807 100644
--- a/src/FDM/LaRCsim.cxx
+++ b/src/FDM/LaRCsim.cxx
@@ -35,7 +35,7 @@
 #include "LaRCsim.hxx"
 
 
-#define USE_NEW_ENGINE_CODE 1
+// #define USE_NEW_ENGINE_CODE 1
 FGEngine eng;