diff --git a/src/calibre/db/annotations.py b/src/calibre/db/annotations.py
index 1168c80e71..fa695e3075 100644
--- a/src/calibre/db/annotations.py
+++ b/src/calibre/db/annotations.py
@@ -11,6 +11,11 @@ from polyglot.builtins import itervalues
 no_cfi_sort_key = cfi_sort_key('/99999999')
 
 
+def unicode_normalize(text):
+    from unicodedata import normalize
+    return normalize('NFKC', text)
+
+
 def bookmark_sort_key(b):
     if b.get('pos_type') == 'epubcfi':
         return cfi_sort_key(b['pos'], only_path=False)
@@ -125,4 +130,4 @@ def annot_db_data(annot):
         notes = annot.get('notes') or ''
         if notes:
             text += '\n\x1f\n' + notes
-    return aid, text
+    return aid, unicode_normalize(text)
diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index 6527b6e817..a108b6d173 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -19,7 +19,7 @@ from calibre.constants import (iswindows, filesystem_encoding,
         preferred_encoding)
 from calibre.ptempfile import PersistentTemporaryFile, TemporaryFile
 from calibre.db import SPOOL_SIZE
-from calibre.db.annotations import annot_db_data
+from calibre.db.annotations import annot_db_data, unicode_normalize
 from calibre.db.schema_upgrades import SchemaUpgrade
 from calibre.db.delete_service import delete_service
 from calibre.db.errors import NoSuchFormat
@@ -1801,6 +1801,7 @@ class DB(object):
         fts_engine_query, use_stemming, highlight_start, highlight_end, snippet_size, annotation_type,
         restrict_to_book_ids, restrict_to_user, ignore_removed=False
     ):
+        fts_engine_query = unicode_normalize(fts_engine_query)
         fts_table = 'annotations_fts_stemmed' if use_stemming else 'annotations_fts'
         text = 'annotations.searchable_text'
         if highlight_start is not None and highlight_end is not None:
diff --git a/src/calibre/db/tests/fts.py b/src/calibre/db/tests/fts.py
index e1874444c5..8f49afe96b 100644
--- a/src/calibre/db/tests/fts.py
+++ b/src/calibre/db/tests/fts.py
@@ -9,6 +9,7 @@ from apsw import Connection
 
 from calibre.constants import plugins
 from calibre.db.tests.base import BaseTest
+from calibre.db.annotations import unicode_normalize
 
 
 def print(*args, **kwargs):
@@ -35,7 +36,7 @@ CREATE VIRTUAL TABLE fts_row USING fts5vocab(fts_table, row);
         return self.cursor().execute(*a)
 
     def insert_text(self, text):
-        self.execute('INSERT INTO fts_table(t) VALUES (?)', (text,))
+        self.execute('INSERT INTO fts_table(t) VALUES (?)', (unicode_normalize(text),))
 
     def term_row_counts(self):
         return dict(self.execute('SELECT term,doc FROM fts_row'))
@@ -46,14 +47,14 @@ CREATE VIRTUAL TABLE fts_row USING fts5vocab(fts_table, row);
             f'SELECT snippet(fts_table, 0, "{highlight_start}", "{highlight_end}", "…", {snippet_size})'
             ' FROM fts_table WHERE fts_table MATCH ? ORDER BY RANK'
         )
-        return list(self.execute(stmt, (query,)))
+        return list(self.execute(stmt, (unicode_normalize(query),)))
 
 
 def tokenize(text, flags=None, remove_diacritics=True):
     from calibre_extensions.sqlite_extension import tokenize, FTS5_TOKENIZE_DOCUMENT
     if flags is None:
         flags = FTS5_TOKENIZE_DOCUMENT
-    return tokenize(text, remove_diacritics, flags)
+    return tokenize(unicode_normalize(text), remove_diacritics, flags)
 
 
 class FTSTest(BaseTest):