diff --git a/addons/web/static/src/js/views/graph/graph_renderer.js b/addons/web/static/src/js/views/graph/graph_renderer.js
index 0517e14c876..5deba9d69bd 100644
--- a/addons/web/static/src/js/views/graph/graph_renderer.js
+++ b/addons/web/static/src/js/views/graph/graph_renderer.js
@@ -332,8 +332,8 @@ return AbstractRenderer.extend({
         var self = this;
 
         // Remove Undefined of first GroupBy
-        var graphData = _.filter(this.state.data, function(elem){
-            return elem.labels[0] !== undefined;
+        var graphData = _.filter(this.state.data, function (elem) {
+            return elem.labels[0] !== undefined && elem.labels[0] !== _t("Undefined");
         });
 
         // undefined label value becomes a string 'Undefined' translated
@@ -386,10 +386,9 @@ return AbstractRenderer.extend({
             var tick = 0;
             var serie, tickLabel;
             var identity = function (p) {return p;};
-
-            for (var i = 0; i < this.state.data.length; i++) {
+            for (var i = 0; i < graphData.length; i++) {
                 if (graphData[i].labels[0] !== tickLabel) {
-                    tickLabel = this.state.data[i].labels[0];
+                    tickLabel = graphData[i].labels[0];
                     ticksLabels.push(tickLabel);
                     tick++;
                 }
diff --git a/addons/web/static/tests/views/graph_tests.js b/addons/web/static/tests/views/graph_tests.js
index 6dcafc20072..afa3ea9d0ef 100644
--- a/addons/web/static/tests/views/graph_tests.js
+++ b/addons/web/static/tests/views/graph_tests.js
@@ -762,7 +762,7 @@ QUnit.module('Views', {
 
     QUnit.test('Undefined should appear in bar, pie graph but not in line graph', function (assert) {
         assert.expect(4);
-        
+
         var graph = createView({
             View: GraphView,
             model: "foo",
@@ -773,13 +773,40 @@ QUnit.module('Views', {
                 '</graph>',
         });
 
-        assert.strictEqual(graph.$("svg.nvd3-svg:contains('Undefined')").length, 0);
-        assert.strictEqual(graph.$("svg.nvd3-svg:contains('March')").length, 1);
-
-        graph.$buttons.find('.o_graph_button[data-mode=bar]').click();
-        assert.strictEqual(graph.$("svg.nvd3-svg:contains('Undefined')").length, 1);
+        assert.strictEqual(graph.$("svg.nvd3-svg .nv-x:contains('Undefined')").length, 0);
         assert.strictEqual(graph.$("svg.nvd3-svg:contains('January')").length, 1);
 
+        graph.$buttons.find('.o_graph_button[data-mode=bar]').click();
+        assert.strictEqual(graph.$("svg.nvd3-svg .nv-x:contains('Undefined')").length, 1);
+        assert.strictEqual(graph.$("svg.nvd3-svg:contains('January')").length, 1);
+
+        graph.destroy();
+    });
+
+    QUnit.test('Undefined should appear in bar, pie graph but not in line graph with multiple groupbys', function (assert) {
+        assert.expect(6);
+
+        var graph = createView({
+            View: GraphView,
+            model: "foo",
+            groupBy:['date', 'color_id'],
+            data: this.data,
+            arch: '<graph string="Partners" type="line">' +
+                        '<field name="bar"/>' +
+                '</graph>',
+        });
+
+        assert.strictEqual(graph.$("svg.nvd3-svg .nv-x:contains('Undefined')").length, 0);
+        assert.strictEqual(graph.$("svg.nvd3-svg:contains('January')").length, 1);
+
+        graph.$buttons.find('.o_graph_button[data-mode=bar]').click();
+        assert.strictEqual(graph.$("svg.nvd3-svg .nv-x:contains('Undefined')").length, 1);
+        assert.strictEqual(graph.$("svg.nvd3-svg:contains('January')").length, 1);
+
+        // Undefined should not appear after switching back to line chart
+        graph.$buttons.find('.o_graph_button[data-mode=line]').click();
+        assert.strictEqual(graph.$("svg.nvd3-svg .nv-x:contains('Undefined')").length, 0);
+        assert.strictEqual(graph.$("svg.nvd3-svg:contains('January')").length, 1);
         graph.destroy();
     });
 });