Index: /issm/trunk-jpl/src/m/classes/mask.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/mask.py	(revision 15410)
+++ /issm/trunk-jpl/src/m/classes/mask.py	(revision 15411)
@@ -56,7 +56,8 @@
 		WriteData(fid,'object',self,'fieldname','vertexongroundedice','format','DoubleMat','mattype',1)
 		WriteData(fid,'object',self,'fieldname','vertexonwater','format','DoubleMat','mattype',1)
-		icelevelset=numpy.ones(md.mesh.numberofvertices,int)
-		pos=md.diagnostic.icefront[:,:-2]
-		icelevelset[pos[:]-1]=0;
+		icelevelset=numpy.ones(md.mesh.numberofvertices,float)
+		if numpy.any(numpy.logical_not(numpy.isnan(md.diagnostic.icefront))):
+			pos=md.diagnostic.icefront[:,:-2]
+			icelevelset[pos[:]-1]=0;
 		WriteData(fid,'data',icelevelset,'format','DoubleMat','mattype',1,'enum',IcelevelsetEnum())
 	# }}}