diff --git a/chrome/content/zotero/xpcom/data/item.js b/chrome/content/zotero/xpcom/data/item.js
index 64248dfdb..9faf5d97e 100644
--- a/chrome/content/zotero/xpcom/data/item.js
+++ b/chrome/content/zotero/xpcom/data/item.js
@@ -2742,15 +2742,21 @@ Zotero.Item.prototype.renameAttachmentFile = function(newName, overwrite) {
 		// Ignore if no change
 		//
 		// Note: Just comparing file.leafName to newName isn't reliable
-		if (file.leafName == dest.leafName) {
+		if (file.leafName === dest.leafName) {
 			return true;
 		}
 		
-		if (overwrite) {
-			dest.remove(false);
-		}
-		else if (dest.exists()) {
-			return -1;
+		// If old and new names differ only in case, let's bank on this
+		// just being a case change and not bother checking for existing
+		// files, since dest.exists() will just show true on a case-insensitive
+		// filesystem anyway.
+		if (file.leafName.toLowerCase() != dest.leafName.toLowerCase()) {
+			if (overwrite) {
+				dest.remove(false);
+			}
+			else if (dest.exists()) {
+				return -1;
+			}
 		}
 		
 		file.moveTo(null, newName);
diff --git a/chrome/content/zotero/zoteroPane.js b/chrome/content/zotero/zoteroPane.js
index 70bcc4688..da39c09d2 100644
--- a/chrome/content/zotero/zoteroPane.js
+++ b/chrome/content/zotero/zoteroPane.js
@@ -3684,9 +3684,9 @@ var ZoteroPane = new function()
 			var parentItemID = item.getSource();
 			var newName = Zotero.Attachments.getFileBaseNameFromItem(parentItemID);
 			
-			var ext = file.leafName.match(/[^\.]+$/);
+			var ext = file.leafName.match(/\.[^\.]+$/);
 			if (ext) {
-				newName = newName + '.' + ext;
+				newName = newName + ext;
 			}
 			
 			var renamed = item.renameAttachmentFile(newName);