diff --git a/src/components/colorscale/calc.js b/src/components/colorscale/calc.js
index fe300909f5d..8d095e8642d 100644
--- a/src/components/colorscale/calc.js
+++ b/src/components/colorscale/calc.js
@@ -27,9 +27,12 @@ module.exports = function calc(trace, vals, containerStr, cLetter) {
         inputContainer = trace._input;
     }
 
-    var auto = container[cLetter + 'auto'],
-        min = container[cLetter + 'min'],
-        max = container[cLetter + 'max'],
+    var autoAttr = cLetter + 'auto',
+        minAttr = cLetter + 'min',
+        maxAttr = cLetter + 'max',
+        auto = container[autoAttr],
+        min = container[minAttr],
+        max = container[maxAttr],
         scl = container.colorscale;
 
     if(auto !== false || min === undefined) {
@@ -45,11 +48,21 @@ module.exports = function calc(trace, vals, containerStr, cLetter) {
         max += 0.5;
     }
 
-    container[cLetter + 'min'] = min;
-    container[cLetter + 'max'] = max;
+    container[minAttr] = min;
+    container[maxAttr] = max;
 
-    inputContainer[cLetter + 'min'] = min;
-    inputContainer[cLetter + 'max'] = max;
+    inputContainer[minAttr] = min;
+    inputContainer[maxAttr] = max;
+
+    /*
+     * If auto was explicitly false but min or max was missing,
+     * we filled in the missing piece here but later the trace does
+     * not look auto.
+     * Otherwise make sure the trace still looks auto as far as later
+     * changes are concerned.
+     */
+    inputContainer[autoAttr] = (auto !== false ||
+        (min === undefined && max === undefined));
 
     if(container.autocolorscale) {
         if(min * max < 0) scl = scales.RdBu;
diff --git a/src/plot_api/plot_api.js b/src/plot_api/plot_api.js
index c3860746323..d3f652a3c53 100644
--- a/src/plot_api/plot_api.js
+++ b/src/plot_api/plot_api.js
@@ -1599,7 +1599,10 @@ function _restyle(gd, aobj, _traces) {
             flags.docolorbars = true;
         }
 
-        if(recalcAttrs.indexOf(ai) !== -1) {
+        var aiArrayStart = ai.indexOf('['),
+            aiAboveArray = aiArrayStart === -1 ? ai : ai.substr(0, aiArrayStart);
+
+        if(recalcAttrs.indexOf(aiAboveArray) !== -1) {
             // major enough changes deserve autoscale, autobin, and
             // non-reversed axes so people don't get confused
             if(['orientation', 'type'].indexOf(ai) !== -1) {
@@ -1622,8 +1625,8 @@ function _restyle(gd, aobj, _traces) {
             }
             flags.docalc = true;
         }
-        else if(replotAttrs.indexOf(ai) !== -1) flags.doplot = true;
-        else if(autorangeAttrs.indexOf(ai) !== -1) flags.docalcAutorange = true;
+        else if(replotAttrs.indexOf(aiAboveArray) !== -1) flags.doplot = true;
+        else if(autorangeAttrs.indexOf(aiAboveArray) !== -1) flags.docalcAutorange = true;
     }
 
     // do we need to force a recalc?
diff --git a/src/traces/contour/calc.js b/src/traces/contour/calc.js
index fa0946363d0..07e86c2f2fc 100644
--- a/src/traces/contour/calc.js
+++ b/src/traces/contour/calc.js
@@ -42,7 +42,15 @@ module.exports = function calc(gd, trace) {
         }
 
         // copy auto-contour info back to the source data.
-        trace._input.contours = extendFlat({}, contours);
+        // previously we copied the whole contours object back, but that had
+        // other info (coloring, showlines) that should be left to supplyDefaults
+        if(!trace._input.contours) trace._input.contours = {};
+        extendFlat(trace._input.contours, {
+            start: contours.start,
+            end: contours.end,
+            size: contours.size
+        });
+        trace._input.autocontour = true;
     }
     else {
         // sanity checks on manually-supplied start/end/size
diff --git a/test/jasmine/tests/contour_test.js b/test/jasmine/tests/contour_test.js
index bc456c8ac03..764a5d94218 100644
--- a/test/jasmine/tests/contour_test.js
+++ b/test/jasmine/tests/contour_test.js
@@ -296,15 +296,20 @@ describe('contour calc', function() {
             contoursFinal.forEach(function(spec) {
                 var out = _calc({
                     z: [[0, 2], [3, 5]],
-                    contours: contoursIn,
+                    contours: Lib.extendFlat({}, contoursIn),
                     ncontours: spec.inputNcontours
                 }).trace;
 
                 ['start', 'end', 'size'].forEach(function(attr) {
-                    expect(out.contours[attr]).toBe(spec[attr], [contoursIn, attr]);
+                    expect(out.contours[attr]).toBe(spec[attr], [contoursIn, spec.inputNcontours, attr]);
                     // all these get copied back to the input trace
-                    expect(out._input.contours[attr]).toBe(spec[attr], [contoursIn, attr]);
+                    expect(out._input.contours[attr]).toBe(spec[attr], [contoursIn, spec.inputNcontours, attr]);
                 });
+
+                expect(out._input.autocontour).toBe(true);
+                expect(out._input.zauto).toBe(true);
+                expect(out._input.zmin).toBe(0);
+                expect(out._input.zmax).toBe(5);
             });
         });
     });
diff --git a/test/jasmine/tests/plot_api_test.js b/test/jasmine/tests/plot_api_test.js
index 05af47433cd..f50635e555c 100644
--- a/test/jasmine/tests/plot_api_test.js
+++ b/test/jasmine/tests/plot_api_test.js
@@ -282,7 +282,36 @@ describe('Test plot api', function() {
             expect(gd._fullData[0].marker.color).toBe(colorDflt[0]);
             expect(gd._fullData[1].marker.color).toBe(colorDflt[1]);
         });
+    });
+
+    describe('Plotly.restyle unmocked', function() {
+        var gd;
+
+        beforeEach(function() {
+            gd = createGraphDiv();
+        });
 
+        afterEach(function() {
+            destroyGraphDiv();
+        });
+
+        it('should redo auto z/contour when editing z array', function() {
+            Plotly.plot(gd, [{type: 'contour', z: [[1, 2], [3, 4]]}]).then(function() {
+                expect(gd.data[0].zauto).toBe(true, gd.data[0]);
+                expect(gd.data[0].zmin).toBe(1);
+                expect(gd.data[0].zmax).toBe(4);
+
+                expect(gd.data[0].autocontour).toBe(true);
+                expect(gd.data[0].contours).toEqual({start: 1.5, end: 3.5, size: 0.5});
+
+                return Plotly.restyle(gd, {'z[0][0]': 10});
+            }).then(function() {
+                expect(gd.data[0].zmin).toBe(2);
+                expect(gd.data[0].zmax).toBe(10);
+
+                expect(gd.data[0].contours).toEqual({start: 3, end: 9, size: 1});
+            });
+        });
     });
 
     describe('Plotly.deleteTraces', function() {