diff --git a/src/calibre/gui2/metadata/single.py b/src/calibre/gui2/metadata/single.py
index 508bce45ad..07e1ab3ab8 100644
--- a/src/calibre/gui2/metadata/single.py
+++ b/src/calibre/gui2/metadata/single.py
@@ -872,6 +872,7 @@ class MetadataSingleDialog(MetadataSingleDialogBase):  # {{{
 
         self.tabs[0].gb2 = gb = QGroupBox(_('Co&mments'), self)
         gb.l = l = QVBoxLayout()
+        l.setContentsMargins(0, 0, 0, 0)
         gb.setLayout(l)
         l.addWidget(self.comments)
         self.splitter.addWidget(gb)