diff --git a/Examples/Optimisation/runOptimisation.m b/Examples/Optimisation/runOptimisation.m
index bb822eff..b207ac62 100644
--- a/Examples/Optimisation/runOptimisation.m
+++ b/Examples/Optimisation/runOptimisation.m
@@ -120,7 +120,7 @@
 
     p = getScaledParameterVector(simulatorSetup, parameters);
     [vad, gad]   = evalObjectiveBattmo(p, objmatch, simulatorSetup, parameters, 'GradientMethod', 'AdjointAD', options{:});
-    perturbationSize = {1e-10, 1e-5};
+    perturbationSize = 1e-10;
     [vnum, gnum] = evalObjectiveBattmo(p, objmatch, simulatorSetup, parameters, ...
                                        'GradientMethod', 'PerturbationADNUM'  , ...
                                        'PerturbationSize', perturbationSize   , ...
diff --git a/Utilities/Adjoint/evalObjectiveBattmo.m b/Utilities/Adjoint/evalObjectiveBattmo.m
index b2541c5c..db73b450 100644
--- a/Utilities/Adjoint/evalObjectiveBattmo.m
+++ b/Utilities/Adjoint/evalObjectiveBattmo.m
@@ -143,6 +143,8 @@ This file is part of The MATLAB Reservoir Simulation Toolbox (MRST).
             pertsize = opt.PerturbationSize;
             if isempty(pertsize)
                 pertsize = repmat({1e-7}, numel(parameters), 1);
+            elseif ~iscell(pertsize) && numel(pertsize) == 1 % scalar value
+                pertsize = repmat({pertsize}, numel(parameters), 1);
             end
 
             scaledGradient = cell(numel(parameters), 1);