diff --git a/core/flyout_base.ts b/core/flyout_base.ts
index 547dac15ed8..94657ade3ec 100644
--- a/core/flyout_base.ts
+++ b/core/flyout_base.ts
@@ -255,7 +255,7 @@ export abstract class Flyout extends DeleteArea implements IFlyout {
     this.workspace_.setMetricsManager(
         new FlyoutMetricsManager(this.workspace_, this));
 
-    this.workspace_.isFlyout = true;
+    this.workspace_.internalIsFlyout = true;
     // Keep the workspace visibility consistent with the flyout's visibility.
     this.workspace_.setVisible(this.isVisible_);
 
diff --git a/core/mutator.ts b/core/mutator.ts
index de85081c488..1d0ad364b85 100644
--- a/core/mutator.ts
+++ b/core/mutator.ts
@@ -191,7 +191,7 @@ export class Mutator extends Icon {
       workspaceOptions.languageTree = toolbox.convertToolboxDefToJson(quarkXml);
     }
     this.workspace_ = this.newWorkspaceSvg(workspaceOptions);
-    this.workspace_.isMutator = true;
+    this.workspace_.internalIsMutator = true;
     this.workspace_.addChangeListener(eventUtils.disableOrphans);
 
     // Mutator flyouts go inside the mutator workspace's <g> rather than in
diff --git a/core/workspace.ts b/core/workspace.ts
index 0782c0fe611..fca1ce771b6 100644
--- a/core/workspace.ts
+++ b/core/workspace.ts
@@ -61,14 +61,27 @@ export class Workspace implements IASTNodeLocation {
    */
   rendered = false;
 
+  /**
+   * Is this workspace the surface for a flyout?
+   * @internal
+   */
+  internalIsFlyout = false;
+
   /** Is this workspace the surface for a flyout? */
-  isFlyout = false;
+  get isFlyout(): boolean {
+    return this.internalIsFlyout;
+  }
 
   /**
    * Is this workspace the surface for a mutator?
    * @internal
    */
-  isMutator = false;
+  internalIsMutator = false;
+
+  /** Is this workspace the surface for a mutator? */
+  get isMutator(): boolean {
+    return this.internalIsMutator;
+  }
 
   /**
    * Returns `true` if the workspace is currently in the process of a bulk
diff --git a/tests/mocha/workspace_svg_test.js b/tests/mocha/workspace_svg_test.js
index 568b2d2adfe..d30374c10c0 100644
--- a/tests/mocha/workspace_svg_test.js
+++ b/tests/mocha/workspace_svg_test.js
@@ -124,48 +124,6 @@ suite('WorkspaceSvg', function() {
     });
   });
 
-  suite('addTopBlock', function() {
-    setup(function() {
-      this.targetWorkspace = new Blockly.Workspace();
-      this.workspace.isFlyout = true;
-      this.workspace.targetWorkspace = this.targetWorkspace;
-      Blockly.defineBlocksWithJsonArray([{
-        "type": "get_var_block",
-        "message0": "%1",
-        "args0": [
-          {
-            "type": "field_variable",
-            "name": "VAR",
-            "variableTypes": ["", "type1", "type2"],
-          },
-        ],
-      }]);
-    });
-
-    teardown(function() {
-      // Have to dispose of the main workspace after the flyout workspace
-      // because it holds the variable map.
-      // Normally the main workspace disposes of the flyout workspace.
-      workspaceTeardown.call(this, this.targetWorkspace);
-    });
-
-    test('Trivial Flyout is True', function() {
-      this.targetWorkspace.createVariable('name1', '', '1');
-
-      // Flyout.init usually does this binding.
-      this.workspace.variableMap_ = this.targetWorkspace.getVariableMap();
-
-      Blockly.Events.disable();
-      const block = new Blockly.Block(this.workspace, 'get_var_block');
-      block.inputList[0].fieldRow[0].setValue('1');
-      Blockly.Events.enable();
-
-      this.workspace.removeTopBlock(block);
-      this.workspace.addTopBlock(block);
-      assertVariableValues(this.workspace, 'name1', '', '1');
-    });
-  });
-
   suite('Viewport change events', function() {
     function resetEventHistory(eventsFireStub, changeListenerSpy) {
       eventsFireStub.resetHistory();