diff --git a/+quantity/Discrete.m b/+quantity/Discrete.m
index f2ef2c718ecc3bc74cb9ac8b8958078c21cef515..ec7301fec9d1ca4bed03569e9408f7c2084e58ef 100644
--- a/+quantity/Discrete.m
+++ b/+quantity/Discrete.m
@@ -1394,8 +1394,11 @@ classdef  (InferiorClasses = {?quantity.Symbolic}) Discrete ...
 				gridNameNew = [gridNew.name];
 				gridNew = {gridNew.grid};
 			else
-				gridNameNew = misc.ensureString(gridNameNew);				
+				gridNameNew = misc.ensureString(gridNameNew);	
 				gridNew  = misc.ensureIsCell(gridNew);
+				for it = 1:numel(gridNew)
+					assert( isnumeric( [gridNew{it}] ), "The gridNew parameter must be a cell array of numeric arrays." )
+				end
 			end
 		
 			if obj(1).isConstant
@@ -2780,4 +2783,4 @@ classdef  (InferiorClasses = {?quantity.Symbolic}) Discrete ...
 		
 	end % methods (Access = protected)
 	
-end % classdef
\ No newline at end of file
+end % classdef
diff --git a/+unittests/+quantity/testEquidistantDomain.m b/+unittests/+quantity/testEquidistantDomain.m
index cb0b05ee38a4aae9cd926b904aaf25938a8e84eb..92bd866e9974a8f1d18c1f8043bf71f24346a545 100644
--- a/+unittests/+quantity/testEquidistantDomain.m
+++ b/+unittests/+quantity/testEquidistantDomain.m
@@ -40,4 +40,13 @@ EE(1:2) = quantity.Domain();
 EE(1) = e;
 EE(2) = d;
 
+end
+
+function testSubs(testCase)
+
+f = quantity.Discrete((1:5)', quantity.EquidistantDomain("t", 0, 1, "stepNumber", 5));
+f.subs("t", 1)
+f.changeGrid(quantity.Domain("t", linspace(0,1)))
+
+
 end
\ No newline at end of file