diff --git a/src/documents/search/_backend.py b/src/documents/search/_backend.py
index 930a7f48c..aaa4ed395 100644
--- a/src/documents/search/_backend.py
+++ b/src/documents/search/_backend.py
@@ -1043,16 +1043,21 @@ class TantivyBackend:
         excluded from results.
 
         Args:
-            doc_id: Primary key of the reference document
+            doc_id: Primary key of the reference document, or of one of its
+                versions
             user: User for permission filtering (None for no filtering)
             limit: Maximum number of IDs to return (None = all matching docs)
 
         Returns:
             List of similar document IDs (excluding the original)
         """
+        from documents.versioning import root_document_ids
+
         self._ensure_open()
         searcher = self._index.searcher()
 
+        # Only root documents are indexed, so a version stands for its root
+        doc_id = next(iter(root_document_ids([doc_id])), doc_id)
         id_query = tantivy.Query.term_query(self._schema, "id", doc_id)
         results = searcher.search(id_query, limit=1)
 
diff --git a/src/documents/search/_schema.py b/src/documents/search/_schema.py
index 62130c246..cb686eabf 100644
--- a/src/documents/search/_schema.py
+++ b/src/documents/search/_schema.py
@@ -28,7 +28,9 @@ logger = logging.getLogger("paperless.search")
 #      columns dropped. tantivy compares schemas by ordered field list, so an
 #      index built by v1 rejects every write against the v2 schema.
 # v3 - barcodes JSON field for stored barcode contents
-SCHEMA_VERSION: Final[int] = 3
+# v4 - root documents only. Earlier indexes may hold document versions under
+#      their own id and metadata, so they are rebuilt without them.
+SCHEMA_VERSION: Final[int] = 4
 
 # Present in the index directory from the moment a full rebuild starts until it
 # finishes. If a rebuild is interrupted it is left behind, so the half-built
diff --git a/src/documents/tests/search/test_backend.py b/src/documents/tests/search/test_backend.py
index 4350280f7..42c89c7fc 100644
--- a/src/documents/tests/search/test_backend.py
+++ b/src/documents/tests/search/test_backend.py
@@ -1136,6 +1136,34 @@ class TestMoreLikeThis:
         assert 150 not in ids
         assert 151 in ids
 
+    def test_more_like_this_ids_seeded_by_version_uses_root(
+        self,
+        backend: TantivyBackend,
+    ) -> None:
+        """A version is not indexed, so it must be looked up as its root."""
+        root = DocumentFactory.create(
+            title="Important document",
+            content="financial information report",
+        )
+        version = DocumentFactory.create(
+            title="Important document",
+            content="financial information report",
+            root_document=root,
+            version_index=1,
+        )
+        other = DocumentFactory.create(
+            title="Another document",
+            content="financial information report",
+        )
+        backend.add_or_update(root)
+        backend.add_or_update(other)
+
+        ids = backend.more_like_this_ids(doc_id=version.pk, user=None)
+
+        assert other.pk in ids
+        assert root.pk not in ids
+        assert version.pk not in ids
+
 
 class TestSingleton:
     """Test get_backend() and reset_backend() singleton lifecycle."""