diff --git a/macosx/CreatorWindowController.m b/macosx/CreatorWindowController.m
index 48a822875..214d8117a 100644
--- a/macosx/CreatorWindowController.m
+++ b/macosx/CreatorWindowController.m
@@ -204,10 +204,12 @@
         [alert setAlertStyle: NSWarningAlertStyle];
         
         //check common reasons for failure
-        if (![trackerString hasPrefix: @"http://"])
+        NSRange prefixRange = [trackerString rangeOfString: @"://"];
+        NSString * prefix = [trackerString substringToIndex: prefixRange.location];
+        if ([prefix caseInsensitiveCompare: @"http"] != NSOrderedSame)
             [alert setMessageText: NSLocalizedString(@"The tracker address must begin with \"http://\".",
                                                     "Create torrent -> warning -> message")];
-        else if ([trackerString length] == 7) //don't allow blank addresses
+        else if ([trackerString length] == NSMaxRange(prefixRange)) //don't allow blank addresses
             [alert setMessageText: NSLocalizedString(@"The tracker address cannot be blank.", "Create torrent -> warning -> message")];
         else
             [alert setMessageText: NSLocalizedString(@"The tracker address is invalid.", "Create torrent -> warning -> message")];