diff --git a/bundles/org.eclipse.orion.client.core/web/orion/operationsClient.js b/bundles/org.eclipse.orion.client.core/web/orion/operationsClient.js
index 4cc1df0e54..6f7fbbb771 100644
--- a/bundles/org.eclipse.orion.client.core/web/orion/operationsClient.js
+++ b/bundles/org.eclipse.orion.client.core/web/orion/operationsClient.js
@@ -1,6 +1,6 @@
 /*******************************************************************************
  * @license
- * Copyright (c) 2011, 2014 IBM Corporation and others.
+ * Copyright (c) 2011, 2017 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials are made
  * available under the terms of the Eclipse Public License v1.0
  * (http://www.eclipse.org/legal/epl-v10.html), and the Eclipse Distribution
@@ -120,7 +120,9 @@ define(['i18n!orion/operations/nls/messages', "orion/Deferred"], function(messag
                                     }
                                 }
                             }
-                            that._preferenceService.put(NAMESPACE, globalOperations).then(def.resolve, def.reject);
+                            // overriding the preference key's value completely so set it to clear
+                            var options = { clear: true };
+                            that._preferenceService.put(NAMESPACE, globalOperations, options).then(def.resolve, def.reject);
                         });
                     };
                 }(def), function(def) {
diff --git a/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/operations/operationsClientTests.js b/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/operations/operationsClientTests.js
new file mode 100644
index 0000000000..972e97854e
--- /dev/null
+++ b/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/operations/operationsClientTests.js
@@ -0,0 +1,47 @@
+/*******************************************************************************
+ * @license
+ * Copyright (c) 2017 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License v1.0
+ * (http://www.eclipse.org/legal/epl-v10.html), and the Eclipse Distribution
+ * License v1.0 (http://www.eclipse.org/org/documents/edl-v10.html).
+ *
+ * Contributors: IBM Corporation - initial API and implementation
+ * 				 Google Inc. - Casey Flynn (caseyflynn@google.com)
+ ******************************************************************************/
+/*eslint-env browser, amd, mocha*/
+define([
+	"chai/chai",
+	"orion/bootstrap",
+	'orion/serviceregistry',
+	"orion/operationsClient",
+	"orion/progress",
+	"mocha/mocha"
+], function(chai, mBootstrap, mServiceRegistry, mOperationsClient, mProgress) {
+	var assert = chai.assert;
+
+	describe("Operations Client", function() {
+		it("Bug 510646", function(finished) {
+			mBootstrap.startup().then(function(core) {
+				var serviceRegistry = core.serviceRegistry;
+				var operationsClient = new mOperationsClient.OperationsClient(serviceRegistry);
+				var progressService = new mProgress.ProgressService(serviceRegistry, operationsClient);
+				var operation = {};
+				operation.Location = "/task/temp/bug510646";
+				operation.expires = 0;
+				operation.Name = "test";
+				operation.progressMonitor = {};
+				operation.progressMonitor.progress = function() {};
+				progressService.writeOperation(0, operation);
+				return operationsClient.removeCompletedOperations()
+				.then(function() {
+					return operationsClient.getOperations();
+				})
+				.then(function(operations) {
+					assert.equal(Object.keys(operations).length, 0);
+					finished();
+				});
+			})
+		});
+	});
+});
diff --git a/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/uiTests.html b/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/uiTests.html
index 471016fe53..10d3d02e2b 100644
--- a/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/uiTests.html
+++ b/bundles/org.eclipse.orion.client.ui/web/js-tests/ui/uiTests.html
@@ -32,6 +32,7 @@
 			"js-tests/ui/globalSearch/globalSearchTests",
 			"js-tests/ui/HTMLTemplates/HTMLTemplateTests",
 			"js-tests/ui/objects/objectsTests",
+			"js-tests/ui/operations/operationsClientTests",
 			"js-tests/ui/pageUtil/pageUtilTests",
 			"js-tests/ui/searchCrawler/searchCrawlerTests",
 			"js-tests/ui/settings/settingsTests",