diff --git a/src/calibre/ebooks/oeb/transforms/flatcss.py b/src/calibre/ebooks/oeb/transforms/flatcss.py
index 9c08934938..1b678a3fe5 100644
--- a/src/calibre/ebooks/oeb/transforms/flatcss.py
+++ b/src/calibre/ebooks/oeb/transforms/flatcss.py
@@ -371,11 +371,13 @@ class CSSFlattener(object):
         is_drop_cap = (cssdict.get('float', None) == 'left' and 'font-size' in
                        cssdict and len(node) == 0 and node.text and
                        len(node.text) == 1)
-        is_drop_cap = is_drop_cap or (
-            # The docx input plugin generates drop caps that look like this
-            len(node) == 1 and not node.text and len(node[0]) == 0 and
-            node[0].text and not node[0].tail and len(node[0].text) == 1 and
-            'line-height' in cssdict and 'font-size' in cssdict)
+        # Detect drop caps generated by the docx input plugin
+        if (node.tag and node.tag.endswith('}p') and len(node) == 0 and node.text and len(node.text.strip()) == 1 and
+            not node.tail and 'line-height' in cssdict and 'font-size' in cssdict):
+            dp = node.getparent()
+            if dp.tag and dp.tag.endswith('}div') and len(dp) == 1 and not dp.text:
+                if stylizer.style(dp).cssdict().get('float', None) == 'left':
+                    is_drop_cap = True
         if not self.context.disable_font_rescaling and not is_drop_cap:
             _sbase = self.sbase if self.sbase is not None else \
                 self.context.source.fbase