diff --git a/xml2rfc/writers/pdf.py b/xml2rfc/writers/pdf.py
index c8612627..ca9cb77b 100644
--- a/xml2rfc/writers/pdf.py
+++ b/xml2rfc/writers/pdf.py
@@ -166,6 +166,9 @@ def flatten_unicode_spans(self, html):
   tt, code, pre {{
     font-family: {mono-fonts};
   }}
+  sup {{
+    line-height: 0;
+  }}
   @page {{
     size: A4;
     font-size: 12px; /* needed for the page header and footer text */