diff --git a/app/assets/commandLineHandler.js b/app/assets/commandLineHandler.js
index fa7c1d7d32..bd2cda150a 100644
--- a/app/assets/commandLineHandler.js
+++ b/app/assets/commandLineHandler.js
@@ -16,6 +16,12 @@ if (CommandLineOptions.forceDebugLog) {
 }
 
 CommandLineOptions.forceDataDir = cmdLine.handleFlagWithParam("datadir", false);
+// Set here, to be acted upon in xpcom/commandLineHandler.js
+CommandLineOptions.file = cmdLine.handleFlagWithParam("file", false);
+CommandLineOptions.url = cmdLine.handleFlagWithParam("url", false);
+if (CommandLineOptions.url) {
+	CommandLineOptions.url = cmdLine.resolveURI(CommandLineOptions.url);
+}
 
 var processTestOptions = false;
 if (cmdLine.handleFlag("ZoteroTest", false)) {
diff --git a/app/build.sh b/app/build.sh
index dea8e0c641..19c92c2aba 100755
--- a/app/build.sh
+++ b/app/build.sh
@@ -266,8 +266,6 @@ fi
 # Merge preserved files from Firefox
 #
 # components
-mv components/* components-fx
-rmdir components
 mv components-fx components
 
 mv defaults defaults-z
diff --git a/chrome/content/zotero/modules/commandLineOptions.mjs b/chrome/content/zotero/modules/commandLineOptions.mjs
index cf2cb3f361..cfe3f4f3a2 100644
--- a/chrome/content/zotero/modules/commandLineOptions.mjs
+++ b/chrome/content/zotero/modules/commandLineOptions.mjs
@@ -6,6 +6,8 @@ export var CommandLineOptions = {
 	test: false,
 	automatedTest: false,
 	skipBundledFiles: false,
+	file: false,
+	url: false,
 };
 
 export var TestOptions = {
diff --git a/chrome/content/zotero/xpcom/commandLineHandler.js b/chrome/content/zotero/xpcom/commandLineHandler.js
new file mode 100644
index 0000000000..8f40cf689e
--- /dev/null
+++ b/chrome/content/zotero/xpcom/commandLineHandler.js
@@ -0,0 +1,143 @@
+/*
+    ***** BEGIN LICENSE BLOCK *****
+    
+    Copyright © 2009 Center for History and New Media
+                     George Mason University, Fairfax, Virginia, USA
+                     http://zotero.org
+    
+    This file is part of Zotero.
+    
+    Zotero is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+    
+    Zotero is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+    
+    You should have received a copy of the GNU Affero General Public License
+    along with Zotero.  If not, see <http://www.gnu.org/licenses/>.
+    
+	
+	Based on nsChromeExtensionHandler example code by Ed Anuff at
+	http://kb.mozillazine.org/Dev_:_Extending_the_Chrome_Protocol
+	
+    ***** END LICENSE BLOCK *****
+*/
+
+Zotero.CommandLineIngester = {
+	ingest: async function () {
+		const { CommandLineOptions } = ChromeUtils.importESModule("chrome://zotero/content/modules/commandLineOptions.mjs");
+
+		var fileToOpen;
+		// Handle zotero:// and file URIs
+		var uri = CommandLineOptions.url;
+		if (uri) {
+			if (uri.schemeIs("zotero")) {
+				// Check for existing window and focus it
+				var wm = Components.classes["@mozilla.org/appshell/window-mediator;1"]
+					.getService(Components.interfaces.nsIWindowMediator);
+				var win = wm.getMostRecentWindow("navigator:browser");
+				if (win) {
+					win.focus();
+					win.ZoteroPane.loadURI(uri.spec);
+				}
+			}
+			// See below
+			else if (uri.schemeIs("file")) {
+				fileToOpen = OS.Path.fromFileURI(uri.spec);
+			}
+			else {
+				Zotero.debug(`Not handling URL: ${uri.spec}\n\n`);
+			}
+		}
+
+
+		fileToOpen = fileToOpen || CommandLineOptions.file;
+		if (fileToOpen) {
+			var file = Zotero.File.pathToFile(fileToOpen);
+
+			if (file.leafName.substr(-4).toLowerCase() === ".csl"
+				|| file.leafName.substr(-8).toLowerCase() === ".csl.txt") {
+				// Install CSL file
+				Zotero.Styles.install({ file: file.path }, file.path);
+			}
+			else {
+				// Ask before importing
+				var checkState = {
+					value: Zotero.Prefs.get('import.createNewCollection.fromFileOpenHandler')
+				};
+				if (Services.prompt.confirmCheck(null, Zotero.getString('ingester.importFile.title'),
+					Zotero.getString('ingester.importFile.text', [file.leafName]),
+					Zotero.getString('ingester.importFile.intoNewCollection'),
+					checkState)) {
+					Zotero.Prefs.set(
+						'import.createNewCollection.fromFileOpenHandler', checkState.value
+					);
+
+					// Perform file import in front window
+					var wm = Components.classes["@mozilla.org/appshell/window-mediator;1"]
+						.getService(Components.interfaces.nsIWindowMediator);
+					var browserWindow = wm.getMostRecentWindow("navigator:browser");
+					browserWindow.Zotero_File_Interface.importFile({
+						file,
+						createNewCollection: checkState.value
+					});
+				}
+			}
+		}
+
+		CommandLineOptions.url = false;
+		CommandLineOptions.file = false;
+	},
+};
+
+/**
+ * The object representing the Zotero command line handler.
+ * It is only active after Zotero is initialized and there is initial handling
+ * in app/assets/commandLineHandler.js
+ */
+var ZoteroCommandLineHandler = {
+	/* nsICommandLineHandler */
+	handle: async function (cmdLine) {
+		const { Zotero } = ChromeUtils.importESModule("chrome://zotero/content/zotero.mjs");
+		// handler for Zotero integration commands
+		// this is typically used on Windows only, via WM_COPYDATA rather than the command line
+		var agent = cmdLine.handleFlagWithParam("ZoteroIntegrationAgent", false);
+		if (agent) {
+			// Don't open a new window
+			cmdLine.preventDefault = true;
+			
+			var command = cmdLine.handleFlagWithParam("ZoteroIntegrationCommand", false);
+			var docId = cmdLine.handleFlagWithParam("ZoteroIntegrationDocument", false);
+			var templateVersion = parseInt(cmdLine.handleFlagWithParam("ZoteroIntegrationTemplateVersion", false));
+			templateVersion = isNaN(templateVersion) ? 0 : templateVersion;
+			
+			Zotero.Integration.execCommand(agent, command, docId, templateVersion);
+		}
+		
+		await Zotero.CommandLineIngester.ingest();
+	},
+	
+	classID: Components.ID("{531828f8-a16c-46be-b9aa-14845c3b010f}"),
+	contractID: "@zotero.org/command-line-handler;1",
+	QueryInterface: ChromeUtils.generateQI(["nsISupports", "nsICommandLineHandler"]),
+	createInstance(iid) {
+		return this.QueryInterface(iid);
+	},
+};
+
+const Cm = Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
+Cm.registerFactory(
+	ZoteroCommandLineHandler.classID,
+	"command-line-handler",
+	ZoteroCommandLineHandler.contractID,
+	ZoteroCommandLineHandler
+);
+const catman = Cc["@mozilla.org/categorymanager;1"].getService(Ci.nsICategoryManager);
+
+catman.addCategoryEntry("command-line-handler",
+	"m-zotero",
+	ZoteroCommandLineHandler.contractID, false, true);
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 1d682f7750..24df147580 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -416,6 +416,8 @@ Services.scriptloader.loadSubScript("resource://zotero/polyfill.js");
 			
 		Zotero.Standalone.init();
 		await Zotero.initComplete();
+		// Ingest command line arguments that were not handled due to late command line handler registration.
+		Zotero.CommandLineIngester.ingest();
 	};
 	
 	/**
diff --git a/chrome/content/zotero/zotero.mjs b/chrome/content/zotero/zotero.mjs
index 44c1cee9cf..43063d9657 100644
--- a/chrome/content/zotero/zotero.mjs
+++ b/chrome/content/zotero/zotero.mjs
@@ -32,6 +32,7 @@ const Cu = Components.utils;
 /** XPCOM files to be loaded for all modes **/
 const xpcomFilesAll = [
 	'zotero',
+	'commandLineHandler',
 	'intl',
 	'prefs',
 	'dataDirectory',
diff --git a/components/zotero-service.js b/components/zotero-service.js
deleted file mode 100644
index eab929797f..0000000000
--- a/components/zotero-service.js
+++ /dev/null
@@ -1,140 +0,0 @@
-/*
-    ***** BEGIN LICENSE BLOCK *****
-    
-    Copyright © 2009 Center for History and New Media
-                     George Mason University, Fairfax, Virginia, USA
-                     http://zotero.org
-    
-    This file is part of Zotero.
-    
-    Zotero is free software: you can redistribute it and/or modify
-    it under the terms of the GNU Affero General Public License as published by
-    the Free Software Foundation, either version 3 of the License, or
-    (at your option) any later version.
-    
-    Zotero is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU Affero General Public License for more details.
-    
-    You should have received a copy of the GNU Affero General Public License
-    along with Zotero.  If not, see <http://www.gnu.org/licenses/>.
-    
-	
-	Based on nsChromeExtensionHandler example code by Ed Anuff at
-	http://kb.mozillazine.org/Dev_:_Extending_the_Chrome_Protocol
-	
-    ***** END LICENSE BLOCK *****
-*/
-
-/**
- * The class representing the Zotero command line handler
- */
-function ZoteroCommandLineHandler() {}
-ZoteroCommandLineHandler.prototype = {
-	/* nsICommandLineHandler */
-	handle: async function (cmdLine) {
-		// handler for Zotero integration commands
-		// this is typically used on Windows only, via WM_COPYDATA rather than the command line
-		var agent = cmdLine.handleFlagWithParam("ZoteroIntegrationAgent", false);
-		if(agent) {
-			// Don't open a new window
-			cmdLine.preventDefault = true;
-			
-			var command = cmdLine.handleFlagWithParam("ZoteroIntegrationCommand", false);
-			var docId = cmdLine.handleFlagWithParam("ZoteroIntegrationDocument", false);
-			var templateVersion = parseInt(cmdLine.handleFlagWithParam("ZoteroIntegrationTemplateVersion", false));
-			templateVersion = isNaN(templateVersion) ? 0 : templateVersion;
-			
-			zContext.Zotero.Integration.execCommand(agent, command, docId, templateVersion);
-		}
-	
-		var fileToOpen;
-		// Handle zotero:// and file URIs and prevent them from opening a new window
-		var param = cmdLine.handleFlagWithParam("url", false);
-		if (param) {
-			cmdLine.preventDefault = true;
-			
-			var uri = cmdLine.resolveURI(param);
-			if (uri.schemeIs("zotero")) {
-				addInitCallback(function (Zotero) {
-					Zotero.uiReadyPromise
-					.then(function () {
-						// Check for existing window and focus it
-						var wm = Components.classes["@mozilla.org/appshell/window-mediator;1"]
-							.getService(Components.interfaces.nsIWindowMediator);
-						var win = wm.getMostRecentWindow("navigator:browser");
-						if (win) {
-							win.focus();
-							win.ZoteroPane.loadURI(uri.spec)
-						}
-					});
-				});
-			}
-			// See below
-			else if (uri.schemeIs("file")) {
-				fileToOpen = OS.Path.fromFileURI(uri.spec)
-			}
-			else {
-				dump(`Not handling URL: ${uri.spec}\n\n`);
-			}
-		}
-		
-		
-		// In Fx49-based Mac Standalone, if Zotero is closed, an associated file is launched, and
-		// Zotero hasn't been opened before, a -file parameter is passed and two main windows open.
-		// Subsequent file openings when closed result in -url with file:// URLs (converted above)
-		// and don't result in two windows. Here we prevent the double window.
-		param = fileToOpen;
-		if (!param) {
-			param = cmdLine.handleFlagWithParam("file", false);
-			if (param && isMac()) {
-				cmdLine.preventDefault = true;
-			}
-		}
-		if (param) {
-			addInitCallback(function (Zotero) {
-				// Wait to handle things that require the UI until after it's loaded
-				Zotero.uiReadyPromise
-				.then(function () {
-					var file = Zotero.File.pathToFile(param);
-					
-					if(file.leafName.substr(-4).toLowerCase() === ".csl"
-							|| file.leafName.substr(-8).toLowerCase() === ".csl.txt") {
-						// Install CSL file
-						Zotero.Styles.install({ file: file.path }, file.path);
-					} else {
-						// Ask before importing
-						var checkState = {
-							value: Zotero.Prefs.get('import.createNewCollection.fromFileOpenHandler')
-						};
-						if (Services.prompt.confirmCheck(null, Zotero.getString('ingester.importFile.title'),
-								Zotero.getString('ingester.importFile.text', [file.leafName]),
-								Zotero.getString('ingester.importFile.intoNewCollection'),
-								checkState)) {
-							Zotero.Prefs.set(
-								'import.createNewCollection.fromFileOpenHandler', checkState.value
-							);
-							
-							// Perform file import in front window
-							var wm = Components.classes["@mozilla.org/appshell/window-mediator;1"]
-							   .getService(Components.interfaces.nsIWindowMediator);
-							var browserWindow = wm.getMostRecentWindow("navigator:browser");
-							browserWindow.Zotero_File_Interface.importFile({
-								file,
-								createNewCollection: checkState.value
-							});
-						}
-					}
-				});
-			});
-		}
-	},
-	
-	classID: Components.ID("{531828f8-a16c-46be-b9aa-14845c3b010f}"),
-	service: true,
-	_xpcom_categories: [{category:"command-line-handler", entry:"m-zotero"}],
-	QueryInterface: ChromeUtils.generateQI([Components.interfaces.nsICommandLineHandler])
-};
-
-var NSGetFactory = ComponentUtils.generateNSGetFactory([ZoteroService, ZoteroCommandLineHandler]);