diff --git a/src/ui/public/agg_response/point_series/__tests__/_add_to_siri.js b/src/ui/public/agg_response/point_series/__tests__/_add_to_siri.js
index 61ee27681150..0e7042d8a2e3 100644
--- a/src/ui/public/agg_response/point_series/__tests__/_add_to_siri.js
+++ b/src/ui/public/agg_response/point_series/__tests__/_add_to_siri.js
@@ -9,20 +9,20 @@ describe('addToSiri', function () {
   }));
 
   it('creates a new series the first time it sees an id', function () {
-    var series = {};
+    var series = new Map();
     var point = {};
     var id = 'id';
     addToSiri(series, point, id);
 
-    expect(series).to.have.own.property(id);
-    expect(series[id]).to.be.an('object');
-    expect(series[id].label).to.be(id);
-    expect(series[id].values).to.have.length(1);
-    expect(series[id].values[0]).to.be(point);
+    expect(series.has(id)).to.be(true);
+    expect(series.get(id)).to.be.an('object');
+    expect(series.get(id).label).to.be(id);
+    expect(series.get(id).values).to.have.length(1);
+    expect(series.get(id).values[0]).to.be(point);
   });
 
   it('adds points to existing series if id has been seen', function () {
-    var series = {};
+    var series = new Map();
     var id = 'id';
 
     var point = {};
@@ -31,25 +31,25 @@ describe('addToSiri', function () {
     var point2 = {};
     addToSiri(series, point2, id);
 
-    expect(series).to.have.own.property(id);
-    expect(series[id]).to.be.an('object');
-    expect(series[id].label).to.be(id);
-    expect(series[id].values).to.have.length(2);
-    expect(series[id].values[0]).to.be(point);
-    expect(series[id].values[1]).to.be(point2);
+    expect(series.has(id)).to.be(true);
+    expect(series.get(id)).to.be.an('object');
+    expect(series.get(id).label).to.be(id);
+    expect(series.get(id).values).to.have.length(2);
+    expect(series.get(id).values[0]).to.be(point);
+    expect(series.get(id).values[1]).to.be(point2);
   });
 
   it('allows overriding the series label', function () {
-    var series = {};
+    var series = new Map();
     var id = 'id';
     var label = 'label';
     var point = {};
     addToSiri(series, point, id, label);
 
-    expect(series).to.have.own.property(id);
-    expect(series[id]).to.be.an('object');
-    expect(series[id].label).to.be(label);
-    expect(series[id].values).to.have.length(1);
-    expect(series[id].values[0]).to.be(point);
+    expect(series.has(id)).to.be(true);
+    expect(series.get(id)).to.be.an('object');
+    expect(series.get(id).label).to.be(label);
+    expect(series.get(id).values).to.have.length(1);
+    expect(series.get(id).values[0]).to.be(point);
   });
 });
diff --git a/src/ui/public/agg_response/point_series/_add_to_siri.js b/src/ui/public/agg_response/point_series/_add_to_siri.js
index 26a6c1ea3582..df50b11f6c7e 100644
--- a/src/ui/public/agg_response/point_series/_add_to_siri.js
+++ b/src/ui/public/agg_response/point_series/_add_to_siri.js
@@ -3,15 +3,15 @@ define(function (require) {
     return function addToSiri(series, point, id, label) {
       id = id == null ? '' : id + '';
 
-      if (series[id]) {
-        series[id].values.push(point);
+      if (series.has(id)) {
+        series.get(id).values.push(point);
         return;
       }
 
-      series[id] = {
+      series.set(id, {
         label: label == null ? id : label,
         values: [point]
-      };
+      });
     };
   };
 });
diff --git a/src/ui/public/agg_response/point_series/_get_series.js b/src/ui/public/agg_response/point_series/_get_series.js
index a8089ba7a6d6..7e86ecf67ba2 100644
--- a/src/ui/public/agg_response/point_series/_get_series.js
+++ b/src/ui/public/agg_response/point_series/_get_series.js
@@ -29,8 +29,8 @@ define(function (require) {
           addToSiri(series, point, seriesId, seriesLabel);
         });
 
-      }, {})
-      .values()
+      }, new Map())
+      .thru(series => [...series.values()])
       .value();
 
       if (multiY) {