diff --git a/src/calibre/ebooks/oeb/polish/cover.py b/src/calibre/ebooks/oeb/polish/cover.py
index 8c6871de53..77f471338b 100644
--- a/src/calibre/ebooks/oeb/polish/cover.py
+++ b/src/calibre/ebooks/oeb/polish/cover.py
@@ -40,8 +40,14 @@ def get_azw3_raster_cover_name(container):
 
 def mark_as_cover_azw3(container, name):
     href = container.name_to_href(name, container.opf_name)
+    found = False
     for item in container.opf_xpath('//opf:guide/opf:reference[@href and contains(@type, "cover")]'):
         item.set('href', href)
+        found = True
+    if not found:
+        for guide in container.opf_xpath('//opf:guide'):
+            container.insert_into_xml(guide, guide.makeelement(
+                OPF('reference'), href=href, type='cover'))
     container.dirty(container.opf_name)
 
 def get_raster_cover_name(container):