Index: /issm/trunk-jpl/src/m/classes/SMBpdd.py
===================================================================
--- /issm/trunk-jpl/src/m/classes/SMBpdd.py	(revision 18734)
+++ /issm/trunk-jpl/src/m/classes/SMBpdd.py	(revision 18735)
@@ -94,7 +94,7 @@
 			md = checkfield(md,'fieldname','surfaceforcings.rlaps','>=',0,'numel',[1]);
 			md = checkfield(md,'fieldname','surfaceforcings.rlapslgm','>=',0,'numel',[1]);
-			md = checkfield(md,'fieldname','surfaceforcings.Pfac','NaN',1,'size',[2,NaN]);
-			md = checkfield(md,'fieldname','surfaceforcings.Tdiff','NaN',1,'size',[2,NaN]);
-			md = checkfield(md,'fieldname','surfaceforcings.sealev','NaN',1,'size',[2,NaN]);
+			md = checkfield(md,'fieldname','surfaceforcings.Pfac','NaN',1,'size',[2,numpy.nan]);
+			md = checkfield(md,'fieldname','surfaceforcings.Tdiff','NaN',1,'size',[2,numpy.nan]);
+			md = checkfield(md,'fieldname','surfaceforcings.sealev','NaN',1,'size',[2,numpy.nan]);
 			if not self.isdelta18o:
 				md = checkfield(md,'fieldname','surfaceforcings.monthlytemperatures','forcing',1,'NaN',1)