diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index 1d9ff43..aee797d 100644
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -626,7 +626,9 @@
     # and prepend to _tryorder
     for cmdline in _userchoices:
         if cmdline != '':
-            _synthesize(cmdline, -1)
+            cmd = _synthesize(cmdline, -1)
+            if cmd[1] is None:
+                register(cmdline, None, GenericBrowser(cmdline), -1)
     cmdline = None # to make del work if _userchoices was empty
     del cmdline
     del _userchoices