diff --git a/chrome/content/zotero/preferences/preferences.xul b/chrome/content/zotero/preferences/preferences.xul
index 0db310ca7d..97ec19bf46 100644
--- a/chrome/content/zotero/preferences/preferences.xul
+++ b/chrome/content/zotero/preferences/preferences.xul
@@ -49,6 +49,7 @@ To add a new preference:
 			<preference id="pref-statusBarIcon" name="extensions.zotero.statusBarIcon" type="int"/>
 			<preference id="pref-automaticScraperUpdates" name="extensions.zotero.automaticScraperUpdates" type="bool"/>
 			<preference id="pref-reportTranslationFailure" name="extensions.zotero.reportTranslationFailure" type="bool"/>
+			<preference id="pref-zoteroDotOrgVersionHeader" name="extensions.zotero.zoteroDotOrgVersionHeader" type="bool"/>
 			<preference id="pref-parseEndNoteMIMETypes" name="extensions.zotero.parseEndNoteMIMETypes" type="bool" onchange="Zotero.Ingester.MIMEHandler.init()"/>
 			<preference id="pref-automaticSnapshots" name="extensions.zotero.automaticSnapshots" type="bool"/>
 			<preference id="pref-downloadAssociatedFiles" name="extensions.zotero.downloadAssociatedFiles" type="bool"/>
@@ -118,6 +119,10 @@ To add a new preference:
 			</hbox>
 			
 			<checkbox label="&zotero.preferences.reportTranslationFailure;" preference="pref-reportTranslationFailure"/>
+			<!-- TODO: localize -->
+			<checkbox label="Allow zotero.org to customize content based on current Zotero version"
+				tooltiptext="If enabled, the current Zotero version will be added to HTTP requests to zotero.org."
+				preference="pref-zoteroDotOrgVersionHeader"/>
 			<checkbox label="&zotero.preferences.parseRISRefer;" preference="pref-parseEndNoteMIMETypes"/>
 			<checkbox label="&zotero.preferences.automaticSnapshots;" preference="pref-automaticSnapshots"/>
 			<checkbox label="&zotero.preferences.downloadAssociatedFiles;" preference="pref-downloadAssociatedFiles"/>
diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 42134eec0d..33a4553e9e 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -215,6 +215,8 @@ var Zotero = new function(){
 			return;
 		}
 		
+		Zotero.VersionHeader.init();
+		
 		// Initialize keyboard shortcuts
 		Zotero.Keys.init();
 		
@@ -1042,6 +1044,15 @@ Zotero.Prefs = new function(){
 					Zotero.Schema.stopRepositoryTimer();
 				}
 				break;
+			
+			case "zoteroDotOrgVersionHeader":
+				if (this.get("zoteroDotOrgVersionHeader")) {
+					Zotero.VersionHeader.register();
+				}
+				else {
+					Zotero.VersionHeader.unregister();
+				}
+				break;
 		}
 	}
 }
@@ -1141,6 +1152,46 @@ Zotero.Keys = new function() {
 }
 
 
+/**
+ * Add X-Zotero-Version header to HTTP requests to zotero.org
+ *
+ * @namespace
+ */
+Zotero.VersionHeader = {
+	init: function () {
+		if (Zotero.Prefs.get("zoteroDotOrgVersionHeader")) {
+			this.register();
+		}
+	},
+	
+	// Called from this.init() and Zotero.Prefs.observe()
+	register: function () {
+		var observerService = Components.classes["@mozilla.org/observer-service;1"]
+								.getService(Components.interfaces.nsIObserverService);
+		observerService.addObserver(this, "http-on-modify-request", false);
+	},
+	
+	observe: function (subject, topic, data) {
+		try {
+			var channel = subject.QueryInterface(Components.interfaces.nsIHttpChannel);
+			if (channel.URI.host.match(/zotero\.org$/)) {
+				channel.setRequestHeader("X-Zotero-Version", Zotero.version, false);
+			}
+		}
+		catch (e) {
+			Zotero.debug(e);
+		}
+	},
+	
+	unregister: function () {
+		var observerService = Components.classes["@mozilla.org/observer-service;1"]
+								.getService(Components.interfaces.nsIObserverService);
+		observerService.removeObserver(this, "http-on-modify-request");
+	}
+}
+
+
+
 /**
 * Class for creating hash arrays that behave a bit more sanely
 *
diff --git a/defaults/preferences/zotero.js b/defaults/preferences/zotero.js
index ec66dbf87a..55d2daeebe 100644
--- a/defaults/preferences/zotero.js
+++ b/defaults/preferences/zotero.js
@@ -14,6 +14,7 @@ pref("extensions.zotero.debug.log",false);
 pref("extensions.zotero.debug.level",5);
 pref("extensions.zotero.debug.time", false);
 pref("extensions.zotero.automaticScraperUpdates",true);
+pref("extensions.zotero.zoteroDotOrgVersionHeader", true);
 pref("extensions.zotero.cacheTranslatorData",true);
 pref("extensions.zotero.zoteroPaneOnTop",false);
 pref("extensions.zotero.statusBarIcon", 2);