Index: /issm/trunk/externalpackages/m1qn3/install.sh
===================================================================
--- /issm/trunk/externalpackages/m1qn3/install.sh	(revision 19134)
+++ /issm/trunk/externalpackages/m1qn3/install.sh	(revision 19135)
@@ -17,4 +17,7 @@
 else
 	FC="gfortran"
+	if [ `uname` == "Darwin" ]; then
+		FC="gfortran -arch x86_64"
+	fi
 fi