diff --git a/chrome/content/zotero/xpcom/schema.js b/chrome/content/zotero/xpcom/schema.js
index 2b469ea25..d637e83f9 100644
--- a/chrome/content/zotero/xpcom/schema.js
+++ b/chrome/content/zotero/xpcom/schema.js
@@ -2447,6 +2447,10 @@ Zotero.Schema = new function(){
 					Zotero.DB.query("UPDATE itemAttachments SET storageModTime=NULL WHERE storageModTime<0");
 				}
 				
+				if (i==62) {
+					Zotero.DB.query("CREATE INDEX IF NOT EXISTS itemData_fieldID ON itemData(fieldID)");
+				}
+				
 				Zotero.wait();
 			}
 			
diff --git a/userdata.sql b/userdata.sql
index fbeb0c50d..9cec5b917 100644
--- a/userdata.sql
+++ b/userdata.sql
@@ -1,4 +1,4 @@
--- 61
+-- 62
 
 -- This file creates tables containing user-specific data for new users --
 -- any changes made here must be mirrored in transition steps in schema.js::_migrateSchema()
@@ -46,6 +46,7 @@ CREATE TABLE itemData (
     FOREIGN KEY (fieldID) REFERENCES fields(fieldID),
     FOREIGN KEY (valueID) REFERENCES itemDataValues(valueID)
 );
+CREATE INDEX itemData_fieldID ON itemData(fieldID);
 
 -- Note data for note and attachment items
 CREATE TABLE itemNotes (