diff --git a/platform/features/plot/src/elements/PlotAxis.js b/platform/features/plot/src/elements/PlotAxis.js
index ff48af6e99..29e67d1976 100644
--- a/platform/features/plot/src/elements/PlotAxis.js
+++ b/platform/features/plot/src/elements/PlotAxis.js
@@ -92,7 +92,7 @@ define(
                     if (!optionKeys[key] && !newOptions[key]) {
                         toAdd.push(option);
                     }
-                    newOptions[option.key] = true;
+                    newOptions[key] = true;
                 });
             });
 
diff --git a/platform/features/plot/test/elements/PlotAxisSpec.js b/platform/features/plot/test/elements/PlotAxisSpec.js
index f4419096e4..f06f0c69cc 100644
--- a/platform/features/plot/test/elements/PlotAxisSpec.js
+++ b/platform/features/plot/test/elements/PlotAxisSpec.js
@@ -30,7 +30,12 @@ define(
         "use strict";
 
         describe("A plot axis", function () {
-            var testMetadatas = [
+            var testMetadatas,
+                testDefault,
+                axis;
+
+            beforeEach(function () {
+                testMetadatas = [
                     {
                         tests: [
                             { key: "t0", name: "T0" },
@@ -52,13 +57,14 @@ define(
                             { key: "t6", name: "T6" }
                         ]
                     }
-                ],
-                testDefault = { key: "test", name: "Test" },
-                controller = new PlotAxis("tests", testMetadatas, testDefault);
+                ];
+                testDefault = { key: "test", name: "Test" };
+                axis = new PlotAxis("tests", testMetadatas, testDefault);
+            });
 
             it("pulls out a list of domain or range options", function () {
                 // Should have filtered out duplicates, etc
-                expect(controller.options).toEqual([
+                expect(axis.options).toEqual([
                     { key: "t0", name: "T0" },
                     { key: "t1", name: "T1" },
                     { key: "t2", name: "T2" },
@@ -70,7 +76,7 @@ define(
             });
 
             it("chooses the first option as a default", function () {
-                expect(controller.active).toEqual({ key: "t0", name: "T0" });
+                expect(axis.active).toEqual({ key: "t0", name: "T0" });
             });
 
             it("falls back to a provided default if no options are present", function () {
@@ -78,6 +84,26 @@ define(
                     .toEqual(testDefault);
             });
 
+            it("allows options to be chosen by key", function () {
+                axis.chooseOption("t3");
+                expect(axis.active).toEqual({ key: "t3", name: "T3" });
+            });
+
+            it("reflects changes to applicable metadata", function () {
+                axis.updateMetadata([ testMetadatas[1] ]);
+                expect(axis.options).toEqual([
+                    { key: "t0", name: "T0" },
+                    { key: "t2", name: "T2" }
+                ]);
+            });
+
+            it("returns the same array instance for unchanged metadata", function () {
+                // ...to avoid triggering extra digest cycles.
+                var oldInstance = axis.options;
+                axis.updateMetadata(testMetadatas);
+                expect(axis.options).toBe(oldInstance);
+            });
+
         });
     }
 );