diff --git a/src/calibre/ebooks/metadata/fetch.py b/src/calibre/ebooks/metadata/fetch.py
index 717d5fd04e..f9cd3c411d 100644
--- a/src/calibre/ebooks/metadata/fetch.py
+++ b/src/calibre/ebooks/metadata/fetch.py
@@ -60,9 +60,7 @@ class MetadataSource(Plugin):
 class GoogleBooks(MetadataSource):
 
     name = 'Google Books'
-
-    def is_ok(self):
-        return bool(self.site_customization)
+    description = _('Downloads metadata from Google Books')
 
     def fetch(self):
         from calibre.ebooks.metadata.google_books import search
@@ -78,6 +76,7 @@ class GoogleBooks(MetadataSource):
 class ISBNDB(MetadataSource):
 
     name = 'IsbnDB'
+    description = _('Downloads metadata from isbndb.com')
 
     def fetch(self):
         if not self.site_customization:
@@ -116,6 +115,7 @@ class Amazon(MetadataSource):
 
     name = 'Amazon'
     metadata_type = 'social'
+    description = _('Downloads social metadata from amazon.com')
 
     def fetch(self):
         if not self.isbn:
diff --git a/src/calibre/gui2/dialogs/fetch_metadata.py b/src/calibre/gui2/dialogs/fetch_metadata.py
index 59192fb466..a9de5b131c 100644
--- a/src/calibre/gui2/dialogs/fetch_metadata.py
+++ b/src/calibre/gui2/dialogs/fetch_metadata.py
@@ -101,7 +101,10 @@ class FetchMetadata(QDialog, Ui_FetchMetadata):
         self.timeout = timeout
         QObject.connect(self.fetch, SIGNAL('clicked()'), self.fetch_metadata)
 
-        self.key.setText(get_isbndb_key())
+        isbndb_key = get_isbndb_key()
+        if not isbndb_key:
+            isbndb_key = ''
+        self.key.setText(isbndb_key)
 
         self.setWindowTitle(title if title else _('Unknown'))
         self.isbn = isbn