diff --git a/chrome/content/zotero/xpcom/db.js b/chrome/content/zotero/xpcom/db.js
index b7801d4d8..2eeab1ddd 100644
--- a/chrome/content/zotero/xpcom/db.js
+++ b/chrome/content/zotero/xpcom/db.js
@@ -265,6 +265,7 @@ Zotero.DBConnection.prototype.getStatement = function (sql, params, checkParams)
 			
 			params.splice(i, 1);
 			i--;
+			lastNullParamIndex--;
 			continue;
 		}
 		if (!params.length) {
diff --git a/chrome/content/zotero/xpcom/schema.js b/chrome/content/zotero/xpcom/schema.js
index d6eb06ab2..b54548295 100644
--- a/chrome/content/zotero/xpcom/schema.js
+++ b/chrome/content/zotero/xpcom/schema.js
@@ -2386,6 +2386,10 @@ Zotero.Schema = new function(){
 					Zotero.DB.query("DROP TABLE tmpEmptyCreators");
 					Zotero.DB.query("DELETE FROM creatorData WHERE firstName='' AND lastName=''");
 				}
+				
+				if (i==56) {
+					Zotero.DB.query("UPDATE itemAttachments SET mimeType=charsetID, charsetID=NULL WHERE charsetID REGEXP '[a-zA-Z0-9\-]+/[a-zA-Z0-9\-]'");
+				}
 			}
 			
 			_updateDBVersion('userdata', toVersion);
diff --git a/userdata.sql b/userdata.sql
index 28936932d..82cc00e7e 100644
--- a/userdata.sql
+++ b/userdata.sql
@@ -1,4 +1,4 @@
--- 55
+-- 56
 
 -- 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()