diff --git a/src/calibre/gui2/convert/__init__.py b/src/calibre/gui2/convert/__init__.py
index 595ef32324..86e9faf69b 100644
--- a/src/calibre/gui2/convert/__init__.py
+++ b/src/calibre/gui2/convert/__init__.py
@@ -27,7 +27,14 @@ def config_widget_for_input_plugin(plugin):
         return importlib.import_module(
                 'calibre.gui2.convert.'+name).PluginWidget
     except ImportError:
-        pass
+        # If this is not a builtin plugin, we have to import it differently
+        try:
+            ans = importlib.import_module(plugin.__module__+'.'+name).PluginWidget
+        except (ImportError, AttributeError):
+            pass
+        else:
+            if issubclass(ans, Widget):
+                return ans
 
 def bulk_defaults_for_input_format(fmt):
     plugin = plugin_for_input_format(fmt)