diff --git a/indigo/analysis/differ.py b/indigo/analysis/differ.py
index 1220ec070..c8a96a93e 100644
--- a/indigo/analysis/differ.py
+++ b/indigo/analysis/differ.py
@@ -209,7 +209,7 @@ def repl(match):
                 return '\xA0' * (b - a)
             del_.text = ws_re.sub(repl, del_.text)
 
-            if ins is None or ins.tag != 'ins' or del_.tail:
+            if del_.tail or ins is None or (ins.tag != 'ins' and not (ins.get('class') or '').startswith('ins ')):
                 ins = del_.makeelement('ins')
                 # non-breaking space
                 ins.text = '\xA0'
diff --git a/indigo/tests/test_differ.py b/indigo/tests/test_differ.py
index f125ec3ee..0623a3b4f 100644
--- a/indigo/tests/test_differ.py
+++ b/indigo/tests/test_differ.py
@@ -71,7 +71,7 @@ def test_inline_tag_added(self):
         )
 
         self.assertEqual(
-            '<p>Some text <span class="diff-pair"><del>bold text and a tail.</del><ins>&#xA0;</ins></span><b class="ins ">bold text</b><ins> and a tail.</ins></p>',
+            '<p>Some text <span class="diff-pair"><del>bold text and a tail.</del><b class="ins ">bold text</b></span><ins> and a tail.</ins></p>',
             diff,
         )