Index: /issm/trunk-jpl/src/m/classes/slr.m
===================================================================
--- /issm/trunk-jpl/src/m/classes/slr.m	(revision 24728)
+++ /issm/trunk-jpl/src/m/classes/slr.m	(revision 24729)
@@ -101,4 +101,11 @@
 				return; 
 			end
+
+			%check that the mask is a maskpsl class type, otherwise, we won't be able to run very far 
+			%with the slr solution: 
+			if ~strcmpi(class(md.mask),'maskpsl'),
+				error('slr error message: model mask should be of the ''maskpsl'' class');
+			end
+
 			md = checkfield(md,'fieldname','slr.deltathickness','NaN',1,'Inf',1,'size',[md.mesh.numberofelements 1]);
 			md = checkfield(md,'fieldname','slr.sealevel','NaN',1,'Inf',1,'size',[md.mesh.numberofvertices 1]);
@@ -151,5 +158,4 @@
 				end
 			end
-
 
 		end % }}}