diff --git a/src/calibre/ebooks/oeb/polish/kepubify.py b/src/calibre/ebooks/oeb/polish/kepubify.py
index a1ab1e5830..1cda24b25c 100644
--- a/src/calibre/ebooks/oeb/polish/kepubify.py
+++ b/src/calibre/ebooks/oeb/polish/kepubify.py
@@ -164,7 +164,7 @@ def add_kobo_spans(inner, root_lang):
             paranum += 1
             segnum = 0
             increment_next_para = False
-        stripped = leading_whitespace_pat.sub('', text)
+        stripped = leading_whitespace_pat.sub('', text) or text
         ws = None
         if num := len(text) - len(stripped):
             ws = text[:num]
diff --git a/src/calibre/ebooks/oeb/polish/tests/kepubify.py b/src/calibre/ebooks/oeb/polish/tests/kepubify.py
index 7e0692f66d..11d51f9b65 100644
--- a/src/calibre/ebooks/oeb/polish/tests/kepubify.py
+++ b/src/calibre/ebooks/oeb/polish/tests/kepubify.py
@@ -59,6 +59,9 @@ div#book-inner {{ margin-top: 0; margin-bottom: 0; }}</style><script type="text/
         suffix =  '</div></div></body></html>'
         for src, expected in {
             # basics
+            '<p>one</p><p>\xa0</p>':
+            '<p><span class="koboSpan" id="kobo.1.1">one</span></p><p><span class="koboSpan" id="kobo.2.1">&#160;</span></p>',
+
             '<p>Simple sentences. In a single paragraph.'
             '<p>A sentence <i>with <b>nested</b>, tailed</i> formatting. Another.':