diff --git a/chrome/content/zotero/xpcom/zotero.js b/chrome/content/zotero/xpcom/zotero.js
index 6f7f52c57..25ca42a96 100644
--- a/chrome/content/zotero/xpcom/zotero.js
+++ b/chrome/content/zotero/xpcom/zotero.js
@@ -36,7 +36,7 @@ const ZOTERO_CONFIG = {
 	API_VERSION: 2,
 	PREF_BRANCH: 'extensions.zotero.',
 	BOOKMARKLET_URL: 'https://www.zotero.org/bookmarklet/',
-	VERSION: "3.1a1.SOURCE"
+	VERSION: "4.0a1.SOURCE"
 };
 
 // Commonly used imports accessible anywhere
diff --git a/install.rdf b/install.rdf
index 16f7a3278..75a125ab1 100644
--- a/install.rdf
+++ b/install.rdf
@@ -6,7 +6,7 @@
   
     <em:id>zotero@chnm.gmu.edu</em:id>
     <em:name>Zotero</em:name>
-    <em:version>3.1a1.SOURCE</em:version>
+    <em:version>4.0a1.SOURCE</em:version>
     <em:creator>Center for History and New Media<br/>George Mason University</em:creator>
     <em:contributor>Dan Cohen</em:contributor>
     <em:contributor>Sean Takats</em:contributor>
diff --git a/update.rdf b/update.rdf
index c1a6928a5..034943baa 100644
--- a/update.rdf
+++ b/update.rdf
@@ -7,7 +7,7 @@
     <RDF:Seq>
       <RDF:li>
         <RDF:Description>
-          <version>3.1a1.SOURCE</version>
+          <version>4.0a1.SOURCE</version>
           <targetApplication>
             <RDF:Description>
               <id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</id>