diff --git a/matlab/reports/@graph/graph.m b/matlab/reports/@graph/graph.m
index d2f1da55d..5f4a2343c 100644
--- a/matlab/reports/@graph/graph.m
+++ b/matlab/reports/@graph/graph.m
@@ -146,10 +146,10 @@ valid_legend_orientations = {'vertical', 'horizontal'};
 assert(any(strcmp(o.legendOrientation, valid_legend_orientations)), ...
        ['@graph.graph: legendOrientation must be one of ' strjoin(valid_legend_orientations, ' ')]);
 
-assert(isempty(o.shade) || (isa(o.shade, 'dates') && o.shade.ndat >= 2), ...
+assert(isempty(o.shade) || (isdates(o.shade) && o.shade.ndat >= 2), ...
        ['@graph.graph: shade is specified as a dates range, e.g. ' ...
         '''dates(''1999q1''):dates(''1999q3'')''.']);
-assert(isempty(o.xrange) || (isa(o.xrange, 'dates') && o.xrange.ndat >= 2), ...
+assert(isempty(o.xrange) || (isdates(o.xrange) && o.xrange.ndat >= 2), ...
        ['@graph.graph: xrange is specified as a dates range, e.g. ' ...
         '''dates(''1999q1''):dates(''1999q3'')''.']);
 assert(isempty(o.yrange) || (isfloat(o.yrange) && length(o.yrange) == 2 && ...
diff --git a/matlab/reports/@report_series/writeSeriesForTable.m b/matlab/reports/@report_series/writeSeriesForTable.m
index a35d0531a..a3999c566 100644
--- a/matlab/reports/@report_series/writeSeriesForTable.m
+++ b/matlab/reports/@report_series/writeSeriesForTable.m
@@ -35,7 +35,7 @@ function o = writeSeriesForTable(o, fid, dates, precision)
 %% Validate options passed to function
 assert(fid ~= -1);
 for i=1:length(dates)
-    assert(isa(dates{i}, 'dates'));
+    assert(isdates(dates{i}));
 end
 assert(isint(precision));
 
diff --git a/matlab/reports/@report_table/report_table.m b/matlab/reports/@report_table/report_table.m
index 8f922f1eb..70b17c9ff 100644
--- a/matlab/reports/@report_table/report_table.m
+++ b/matlab/reports/@report_table/report_table.m
@@ -78,7 +78,7 @@ if ~iscell(o.range)
     o.range = {o.range};
 end
 
-if isa(o.vlineAfter, 'dates')
+if isdates(o.vlineAfter)
     o.vlineAfter = {o.vlineAfter};
 end
 
diff --git a/matlab/reports/allCellsAreDates.m b/matlab/reports/allCellsAreDates.m
index 533ff49e4..7beca1b00 100644
--- a/matlab/reports/allCellsAreDates.m
+++ b/matlab/reports/allCellsAreDates.m
@@ -31,7 +31,7 @@ function tf = allCellsAreDates(dcell)
 assert(iscell(dcell));
 tf = true;
 for i=1:length(dcell)
-    if ~isa(dcell{i}, 'dates')
+    if ~isdates(dcell{i})
         tf = false;
         return;
     end
diff --git a/matlab/reports/allCellsAreDatesRange.m b/matlab/reports/allCellsAreDatesRange.m
index 4a12ac573..fd3e111d8 100644
--- a/matlab/reports/allCellsAreDatesRange.m
+++ b/matlab/reports/allCellsAreDatesRange.m
@@ -31,7 +31,7 @@ function tf = allCellsAreDatesRange(dcell)
 assert(iscell(dcell));
 tf = true;
 for i=1:length(dcell)
-    if ~(isa(dcell{i}, 'dates') && dcell{i}.ndat >= 2)
+    if ~(isdates(dcell{i}) && dcell{i}.ndat >= 2)
         tf = false;
         return;
     end
diff --git a/matlab/reports/display_reporting_object.m b/matlab/reports/display_reporting_object.m
index e0c52d8e6..e8ae950e4 100644
--- a/matlab/reports/display_reporting_object.m
+++ b/matlab/reports/display_reporting_object.m
@@ -69,7 +69,7 @@ for i=1:length(fields)
             fprintf('false');
         end
     elseif isobject(val)
-        if isa(val, 'dates')
+        if isdates(val)
             fprintf('<dates: %s, ..., %s>', ...
                     date2string(val(1)), date2string(val(end)));
         elseif isa(val, 'dseries')