diff --git a/build_vol_cmake.sh b/build_vol_cmake.sh
index 371ee60b..bd2eb1f7 100755
--- a/build_vol_cmake.sh
+++ b/build_vol_cmake.sh
@@ -96,7 +96,7 @@ usage()
     echo
 }
 
-optspec=":hctdmst:H:C:Y:B:P:-"
+optspec=":hctdmstG:H:C:Y:B:P:-"
 while getopts "$optspec" optchar; do
     case "${optchar}" in
     h)