diff --git a/src/calibre/gui2/metadata/basic_widgets.py b/src/calibre/gui2/metadata/basic_widgets.py
index ac41a72def..593a3839ac 100644
--- a/src/calibre/gui2/metadata/basic_widgets.py
+++ b/src/calibre/gui2/metadata/basic_widgets.py
@@ -973,7 +973,7 @@ class IdentifiersEdit(QLineEdit): # {{{
         tt = self.BASE_TT
         extra = ''
         if not isbn:
-            col = 'rgba(0,255,0,0%)'
+            col = 'none'
         elif check_isbn(isbn) is not None:
             col = 'rgba(0,255,0,20%)'
             extra = '\n\n'+_('This ISBN number is valid')
diff --git a/src/calibre/gui2/metadata/single.py b/src/calibre/gui2/metadata/single.py
index 52b9e99872..495c89532c 100644
--- a/src/calibre/gui2/metadata/single.py
+++ b/src/calibre/gui2/metadata/single.py
@@ -156,6 +156,9 @@ class MetadataSingleDialogBase(ResizableDialog):
 
         self.identifiers = IdentifiersEdit(self)
         self.basic_metadata_widgets.append(self.identifiers)
+        self.clear_identifiers_button = QToolButton(self)
+        self.clear_identifiers_button.setIcon(QIcon(I('trash.png')))
+        self.clear_identifiers_button.clicked.connect(self.identifiers.clear)
 
         self.publisher = PublisherEdit(self)
         self.basic_metadata_widgets.append(self.publisher)
@@ -541,8 +544,8 @@ class MetadataSingleDialog(MetadataSingleDialogBase): # {{{
         sto(self.rating, self.tags)
         create_row2(2, self.tags, self.tags_editor_button)
         sto(self.tags_editor_button, self.identifiers)
-        create_row2(3, self.identifiers)
-        sto(self.identifiers, self.timestamp)
+        create_row2(3, self.identifiers, self.clear_identifiers_button)
+        sto(self.clear_identifiers_button, self.timestamp)
         create_row2(4, self.timestamp, self.timestamp.clear_button)
         sto(self.timestamp.clear_button, self.pubdate)
         create_row2(5, self.pubdate, self.pubdate.clear_button)