diff --git a/Exec/science/subchandra/GNUmakefile b/Exec/science/subchandra/GNUmakefile
index c7fe376fd3..f667161d2f 100644
--- a/Exec/science/subchandra/GNUmakefile
+++ b/Exec/science/subchandra/GNUmakefile
@@ -13,6 +13,7 @@ USE_MPI    = TRUE
 
 USE_GRAV   = TRUE
 USE_REACT  = TRUE
+USE_SHOCK_VAR = TRUE
 
 USE_MODEL_PARSER = TRUE