diff --git a/src/fvAgglomerationMethods/Allwmake b/src/fvAgglomerationMethods/Allwmake
index fcccbcbe9a..61d951c8c6 100755
--- a/src/fvAgglomerationMethods/Allwmake
+++ b/src/fvAgglomerationMethods/Allwmake
@@ -3,6 +3,11 @@ cd ${0%/*} || exit 1    # run from this directory
 [ $# -ge 1 ] && makeOption=$1 || makeOption=libso
 set -x
 
-wmake $makeOption MGridGenGamgAgglomeration
+export ParMGridGen=$WM_THIRD_PARTY_DIR/ParMGridGen-1.0
+
+if [ -d "$ParMGridGen/MGridGen/Lib" ]
+then
+    wmake $makeOption MGridGenGamgAgglomeration
+fi
 
 # ----------------------------------------------------------------- end-of-file
diff --git a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/Make/options b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/Make/options
index 80b3169750..a58b65fb79 100644
--- a/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/Make/options
+++ b/src/fvAgglomerationMethods/MGridGenGamgAgglomeration/Make/options
@@ -1,4 +1,4 @@
-ParMGridGen = $(WM_THIRD_PARTY_DIR)/ParMGridGen-1.0
+/* Needs ParMGridGen environment variable set. (see Allwmake script) */
 
 TYPE_REAL=
 #if defined(WM_SP)