diff --git a/src/traces/heatmap/xyz_defaults.js b/src/traces/heatmap/xyz_defaults.js
index d411aa42cdd..8be45ca87f0 100644
--- a/src/traces/heatmap/xyz_defaults.js
+++ b/src/traces/heatmap/xyz_defaults.js
@@ -44,7 +44,10 @@ module.exports = function handleXYZDefaults(traceIn, traceOut, coerce, layout, x
         traceOut._length = null;
     }
 
-    if(traceIn.type === 'heatmapgl') return true; // until we handle calendars for heatmapgl
+    if(
+        traceIn.type === 'heatmapgl' ||
+        traceIn.type === 'contourgl'
+    ) return true; // skip calendars until we handle them in those traces
 
     var handleCalendarDefaults = Registry.getComponentMethod('calendars', 'handleTraceDefaults');
     handleCalendarDefaults(traceIn, traceOut, [xName, yName], layout);
diff --git a/test/jasmine/tests/contourgl_test.js b/test/jasmine/tests/contourgl_test.js
index d77fe1792f1..bdf1a40c936 100644
--- a/test/jasmine/tests/contourgl_test.js
+++ b/test/jasmine/tests/contourgl_test.js
@@ -1,12 +1,17 @@
 var Plotly = require('@lib/index');
 var Lib = require('@src/lib');
 var d3 = require('d3');
+var supplyDefaults = require('@src/traces/heatmapgl').supplyDefaults;
+var Plots = require('@src/plots/plots');
 
 // contourgl is not part of the dist plotly.js bundle initially
 Plotly.register([
     require('@lib/contourgl')
 ]);
 
+var schema = Plotly.PlotSchema.get();
+var attributeList = Object.getOwnPropertyNames(schema.traces.heatmapgl.attributes);
+
 // Test utilities
 var createGraphDiv = require('../assets/create_graph_div');
 var destroyGraphDiv = require('../assets/destroy_graph_div');
@@ -250,3 +255,36 @@ describe('contourgl plots', function() {
         });
     });
 });
+
+describe('heatmapgl supplyDefaults', function() {
+    'use strict';
+
+    var traceIn;
+    var traceOut;
+
+    var defaultColor = '#444';
+    var layout = {
+        font: Plots.layoutAttributes.font,
+        _dfltTitle: {colorbar: 'cb'},
+        _subplots: {cartesian: ['xy'], xaxis: ['x'], yaxis: ['y']}
+    };
+
+    beforeEach(function() {
+        traceOut = {};
+    });
+
+    it('should only coerce attributes that are part of scheme', function() {
+        traceIn = {
+            type: 'contourgl',
+            z: [[0, 1], [1, 0]]
+        };
+
+        supplyDefaults(traceIn, traceOut, defaultColor, layout);
+        var allKeys = Object.getOwnPropertyNames(traceOut);
+        allKeys.forEach(function(key) {
+            if(key[0] !== '_') {
+                expect(attributeList.indexOf(key)).not.toBe(-1, key);
+            }
+        });
+    });
+});