diff --git a/chrome/content/zotero/xpcom/http.js b/chrome/content/zotero/xpcom/http.js
index 55dd43e73c..4ff9675008 100644
--- a/chrome/content/zotero/xpcom/http.js
+++ b/chrome/content/zotero/xpcom/http.js
@@ -376,7 +376,11 @@ Zotero.HTTP = new function() {
 			}
 		}
 		for (var header in headers) {
-			xmlhttp.setRequestHeader(header, headers[header]);
+			// Convert numbers to string to make Sinon happy
+			let value = typeof headers[header] == 'number'
+				? headers[header].toString()
+				: headers[header]
+			xmlhttp.setRequestHeader(header, value);
 		}
 
 		// Set timeout
diff --git a/test/tests/feedItemTest.js b/test/tests/feedItemTest.js
index 054544e348..16748e475e 100644
--- a/test/tests/feedItemTest.js
+++ b/test/tests/feedItemTest.js
@@ -218,7 +218,7 @@ describe("Zotero.FeedItem", function () {
 			yield item.toggleRead(true);
 			assert.isTrue(item.save.called, "item was saved on toggle read");
 			
-			item.save.reset();
+			item.save.resetHistory();
 			
 			yield item.toggleRead(true);
 			assert.isFalse(item.save.called, "item was not saved on toggle read to same state");
diff --git a/test/tests/feedItemsTest.js b/test/tests/feedItemsTest.js
index c318a5cbd3..fc0eae6ff0 100644
--- a/test/tests/feedItemsTest.js
+++ b/test/tests/feedItemsTest.js
@@ -100,7 +100,7 @@ describe("Zotero.FeedItems", function () {
 		});
 		
 		afterEach(function* () {
-			save.reset();
+			save.resetHistory();
 			
 			yield clearFeeds();
 		});
diff --git a/test/tests/integrationTest.js b/test/tests/integrationTest.js
index dc14360708..7269ce1926 100644
--- a/test/tests/integrationTest.js
+++ b/test/tests/integrationTest.js
@@ -355,7 +355,7 @@ describe("Zotero.Integration", function () {
 			});
 			
 			afterEach(function() {
-				setDocumentDataSpy.reset();
+				setDocumentDataSpy.resetHistory();
 			});
 			
 			after(function() {
@@ -385,7 +385,7 @@ describe("Zotero.Integration", function () {
 					} catch (e) {}
 					await initDoc(docID, {style});
 					displayDialogStub.resetHistory();
-					displayAlertStub.reset();
+					displayAlertStub.resetHistory();
 				});
 				
 				after(function* () {
@@ -559,7 +559,7 @@ describe("Zotero.Integration", function () {
 				assert.isTrue(getCiteprocBibliographySpy.calledOnce);
 				
 				assert.equal(getCiteprocBibliographySpy.lastCall.returnValue[0].entry_ids.length, 3);
-				getCiteprocBibliographySpy.reset();
+				getCiteprocBibliographySpy.resetHistory();
 
 				setAddEditItems(testItems[3]);
 				yield execCommand('addEditCitation', docID);
@@ -580,7 +580,7 @@ describe("Zotero.Integration", function () {
 				assert.isTrue(getCiteprocBibliographySpy.calledOnce);
 
 				assert.equal(getCiteprocBibliographySpy.lastCall.returnValue[0].entry_ids.length, 3);
-				getCiteprocBibliographySpy.reset();
+				getCiteprocBibliographySpy.resetHistory();
 
 				sinon.stub(doc, 'cursorInField').resolves(doc.fields[1]);
 				sinon.stub(doc, 'canInsertField').resolves(false);
@@ -603,7 +603,7 @@ describe("Zotero.Integration", function () {
 					displayAlertStub = sinon.stub(DocumentPluginDummy.Document.prototype, 'displayAlert').resolves(0);
 				});	
 				beforeEach(function() {
-					displayAlertStub.reset();
+					displayAlertStub.resetHistory();
 				});
 				after(function() {
 					displayAlertStub.restore();
diff --git a/test/tests/itemTreeViewTest.js b/test/tests/itemTreeViewTest.js
index 5d2eb6630a..838f94ddeb 100644
--- a/test/tests/itemTreeViewTest.js
+++ b/test/tests/itemTreeViewTest.js
@@ -147,7 +147,7 @@ describe("Zotero.ItemTreeView", function() {
 			assert.equal(selected[0], existingItemID);
 			
 			// Reset call count on spy
-			win.ZoteroPane.itemSelected.reset();
+			win.ZoteroPane.itemSelected.resetHistory();
 			
 			// Create item with skipNotifier flag
 			var item = new Zotero.Item('book');
@@ -172,7 +172,7 @@ describe("Zotero.ItemTreeView", function() {
 			assert.equal(selected[0], existingItemID);
 			
 			// Reset call count on spy
-			win.ZoteroPane.itemSelected.reset();
+			win.ZoteroPane.itemSelected.resetHistory();
 			
 			// Create item with skipSelect flag
 			var item = new Zotero.Item('book');
@@ -267,7 +267,7 @@ describe("Zotero.ItemTreeView", function() {
 			itemsView.selection.clearSelection();
 			assert.lengthOf(itemsView.getSelectedItems(), 0);
 			// Reset call count on spy
-			win.ZoteroPane.itemSelected.reset();
+			win.ZoteroPane.itemSelected.resetHistory();
 			
 			// Modify item
 			item.setField('title', 'no select on modify');
@@ -293,7 +293,7 @@ describe("Zotero.ItemTreeView", function() {
 			assert.equal(selected[0], id);
 			
 			// Reset call count on spy
-			win.ZoteroPane.itemSelected.reset();
+			win.ZoteroPane.itemSelected.resetHistory();
 			
 			// Modify item
 			item.setField('title', 'maintain selection on modify');