diff --git a/src/fediblockhole/__init__.py b/src/fediblockhole/__init__.py
index 67b1f06..f1bc354 100755
--- a/src/fediblockhole/__init__.py
+++ b/src/fediblockhole/__init__.py
@@ -307,10 +307,14 @@ def merge_comments(oldcomment:str, newcomment:str) -> str:
     if oldcomment in ['', None] and newcomment in ['', None]:
         return ''
 
-    # If both comments are the same, don't merge
-    if oldcomment == newcomment:
+    # If both comments are the same, or new comment is empty, don't merge
+    if oldcomment == newcomment or newcomment in ['', None]:
         return oldcomment
 
+    # If old comment is empty, just return the new one
+    if oldcomment in ['', None]:
+        return newcomment
+
     # We want to skip duplicate fragments so we don't end up
     # re-concatenating the same strings every time there's an
     # update, causing the comment to grow without bound.
diff --git a/tests/test_merge_comments.py b/tests/test_merge_comments.py
new file mode 100644
index 0000000..a6ae8b1
--- /dev/null
+++ b/tests/test_merge_comments.py
@@ -0,0 +1,68 @@
+""" Test merging of comments
+"""
+import pytest
+
+from fediblockhole import merge_comments
+
+def test_merge_blank_comments():
+    
+    oldcomment = ''
+    newcomment = ''
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == ''
+
+def test_merge_None_comments():
+    
+    oldcomment = None
+    newcomment = None
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == ''
+
+def test_merge_oldstr_newNone():
+    
+    oldcomment = 'fred, bibble'
+    newcomment = None
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_oldempty_newcomment():
+    
+    oldcomment = ''
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_oldNone_newcomment():
+    
+    oldcomment = None
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'fred, bibble'
+
+def test_merge_two_different():
+    
+    oldcomment = 'happy, medium, spinning'
+    newcomment = 'fred, bibble'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'happy, medium, spinning, fred, bibble'
+
+def test_merge_overlaps():
+    
+    oldcomment = 'happy, medium, spinning'
+    newcomment = 'fred, medium, bibble, spinning'
+
+    merged_comment = merge_comments(oldcomment, newcomment)
+
+    assert merged_comment == 'happy, medium, spinning, fred, bibble'
\ No newline at end of file