diff --git a/src/calibre/ebooks/conversion/plumber.py b/src/calibre/ebooks/conversion/plumber.py
index e2bd1128f5..2261d071ed 100644
--- a/src/calibre/ebooks/conversion/plumber.py
+++ b/src/calibre/ebooks/conversion/plumber.py
@@ -46,7 +46,8 @@ class Plumber(object):
         'tags', 'book_producer', 'language'
         ]
 
-    def __init__(self, input, output, log, report_progress=DummyReporter(), dummy=False):
+    def __init__(self, input, output, log, report_progress=DummyReporter(),
+            dummy=False, merge_plugin_recs=True):
         '''
         :param input: Path to input file.
         :param output: Path to output file/directory
@@ -483,7 +484,8 @@ OptionRecommendation(name='language',
             for x in getattr(self, w):
                 temp.add(x.clone())
             setattr(self, w, temp)
-        self.merge_plugin_recommendations()
+        if merge_plugin_recs:
+            self.merge_plugin_recommendations()
 
     @classmethod
     def unarchive(self, path, tdir):
diff --git a/src/calibre/gui2/dialogs/config/__init__.py b/src/calibre/gui2/dialogs/config/__init__.py
index d719f24d66..ba63fa560b 100644
--- a/src/calibre/gui2/dialogs/config/__init__.py
+++ b/src/calibre/gui2/dialogs/config/__init__.py
@@ -41,7 +41,8 @@ class ConfigTabs(QTabWidget):
         log = Log()
         log.outputs = []
 
-        self.plumber = Plumber('dummy.epub', 'dummy.epub', log, dummy=True)
+        self.plumber = Plumber('dummy.epub', 'dummy.epub', log, dummy=True,
+                merge_plugin_recs=False)
 
         def widget_factory(cls):
             return cls(self, self.plumber.get_option_by_name,