diff --git a/CFiles/tzmatlab.h b/CFiles/tzmatlab.h
index 0d2449ae007127c9da3503d1bf202a61c322ffea..b319d3568a1b355156f3b5f012df5efebc1eef04 100644
--- a/CFiles/tzmatlab.h
+++ b/CFiles/tzmatlab.h
@@ -66,7 +66,7 @@
 #define USE_MKL_LIBRARY
 /*******************************************************************************/
 
-// #define NEWVERSIONofDW_SWITCH //If defined, using DW's new switch program (implemented in 2008),
+#define NEWVERSIONofDW_SWITCH //If defined, using DW's new switch program (implemented in 2008),
                                 //  which may be incompatible with previous programs, such as ...\SargentWZ2\EstProbModel\EstimationJuly07USED
                                 //If undef, using the old, working switch program for, say,  ...\SargentWZ2\EstProbModel\EstimationJuly07USED.
                                 //Files that are affected are: cstz.c, kalman.c, optpackage.c,