diff --git a/chrome/content/zotero/overlay.js b/chrome/content/zotero/overlay.js
index f6d7d678bb..7736b0494e 100644
--- a/chrome/content/zotero/overlay.js
+++ b/chrome/content/zotero/overlay.js
@@ -1069,7 +1069,13 @@ var ZoteroPane = new function()
 			{
 				var file = attachment.getFile();
 				if (file){
-					if (Zotero.MIME.fileHasInternalHandler(file))
+					var mimeType = attachment.getAttachmentMimeType();
+					if (mimeType) {
+						var ext = Zotero.File.getExtension(file);
+						var internal = Zotero.MIME.hasInternalHandler(mimeType, ext);
+					}
+					
+					if (internal || Zotero.MIME.fileHasInternalHandler(file))
 					{
 						window.loadURI(attachment.getLocalFileURL());
 					}
diff --git a/chrome/content/zotero/xpcom/attachments.js b/chrome/content/zotero/xpcom/attachments.js
index e49b343234..3f46ff3f8f 100644
--- a/chrome/content/zotero/xpcom/attachments.js
+++ b/chrome/content/zotero/xpcom/attachments.js
@@ -442,7 +442,7 @@ Zotero.Attachments = new function(){
 			// leaving the transaction open if the callback never triggers
 			Zotero.DB.commitTransaction();
 			
-			if (Zotero.MIME.isDocumentType(mimeType)) {
+			if (mimeType == 'text/html') {
 				Zotero.debug('Saving with saveDocument()');
 				wbp.saveDocument(document, file, destDir, mimeType, encodingFlags, false);
 			}
diff --git a/chrome/content/zotero/xpcom/mime.js b/chrome/content/zotero/xpcom/mime.js
index a36c6b6344..d98bb5a59d 100644
--- a/chrome/content/zotero/xpcom/mime.js
+++ b/chrome/content/zotero/xpcom/mime.js
@@ -26,7 +26,6 @@ Zotero.MIME = new function(){
 	this.sniffForBinary = sniffForBinary;
 	this.getMIMETypeFromData = getMIMETypeFromData;
 	this.getMIMETypeFromFile = getMIMETypeFromFile;
-	this.isDocumentType = isDocumentType;
 	this.hasNativeHandler = hasNativeHandler;
 	this.hasInternalHandler = hasInternalHandler;
 	this.fileHasInternalHandler = fileHasInternalHandler;
@@ -42,14 +41,6 @@ Zotero.MIME = new function(){
 		["<?xml", 'text/xml']
 	];
 	
-	// MIME types to be saved as documents
-	var _documentMIMETypes = {
-		'text/html': true,
-		'application/xhtml+xml': true,
-		'text/xml': true,
-		'application/xml': true
-	};
-	
 	// MIME types handled natively by Gecko
 	// DEBUG: There's definitely a better way of getting these
 	var _nativeMIMETypes = {
@@ -58,6 +49,8 @@ Zotero.MIME = new function(){
 		'image/jpeg': true,
 		'image/gif': true,
 		'text/xml': true,
+		'application/xhtml+xml': true,
+		'application/xml': true,
 		'text/plain': true,
 		'application/x-javascript': true
 	};
@@ -146,11 +139,6 @@ Zotero.MIME = new function(){
 	}
 	
 	
-	function isDocumentType(mimeType) {
-		return _documentMIMETypes[mimeType] ? true : false;
-	}
-	
-	
 	/*
 	 * Determine if a MIME type can be handled natively
 	 * or if it needs to be passed off to a plugin or external helper app