diff --git a/spacy/kb.pyx b/spacy/kb.pyx
index 16d63a4d3..fed3009da 100644
--- a/spacy/kb.pyx
+++ b/spacy/kb.pyx
@@ -96,6 +96,8 @@ cdef class KnowledgeBase:
     def initialize_entities(self, int64_t nr_entities):
         self._entry_index = PreshMap(nr_entities + 1)
         self._entries = entry_vec(nr_entities + 1)
+
+    def initialize_vectors(self, int64_t nr_entities):
         self._vectors_table = float_matrix(nr_entities + 1)
 
     def initialize_aliases(self, int64_t nr_aliases):
@@ -154,6 +156,7 @@ cdef class KnowledgeBase:
 
         nr_entities = len(set(entity_list))
         self.initialize_entities(nr_entities)
+        self.initialize_vectors(nr_entities)
 
         i = 0
         cdef KBEntryC entry
@@ -172,8 +175,8 @@ cdef class KnowledgeBase:
                 entry.entity_hash = entity_hash
                 entry.freq = freq_list[i]
 
-                vector_index = self.c_add_vector(entity_vector=vector_list[i])
-                entry.vector_index = vector_index
+                self._vectors_table[i] = entity_vector
+                entry.vector_index = i
 
                 entry.feats_row = -1   # Features table currently not implemented
 
@@ -386,6 +389,7 @@ cdef class KnowledgeBase:
             nr_aliases = header[1]
             entity_vector_length = header[2]
             self.initialize_entities(nr_entities)
+            self.initialize_vectors(nr_entities)
             self.initialize_aliases(nr_aliases)
             self.entity_vector_length = entity_vector_length
 
@@ -509,6 +513,7 @@ cdef class KnowledgeBase:
         reader.read_header(&nr_entities, &entity_vector_length)
 
         self.initialize_entities(nr_entities)
+        self.initialize_vectors(nr_entities)
         self.entity_vector_length = entity_vector_length
 
         # STEP 1: load entity vectors
diff --git a/spacy/tests/pipeline/test_entity_linker.py b/spacy/tests/pipeline/test_entity_linker.py
index b97795344..247443489 100644
--- a/spacy/tests/pipeline/test_entity_linker.py
+++ b/spacy/tests/pipeline/test_entity_linker.py
@@ -154,6 +154,40 @@ def test_kb_serialize(nlp):
             mykb.from_disk(d / "unknown" / "kb")
 
 
+@pytest.mark.issue(9137)
+def test_kb_serialize_2(nlp):
+    v = [5, 6, 7, 8]
+    kb1 = KnowledgeBase(vocab=nlp.vocab, entity_vector_length=4)
+    kb1.set_entities(["E1"], [1], [v])
+    assert kb1.get_vector("E1") == v
+    with make_tempdir() as d:
+        kb1.to_disk(d / "kb")
+        kb2 = KnowledgeBase(vocab=nlp.vocab, entity_vector_length=4)
+        kb2.from_disk(d / "kb")
+        assert kb2.get_vector("E1") == v
+
+
+def test_kb_set_entities(nlp):
+    """ Test that set_entities entirely overwrites the previous set of entities """
+    v = [5, 6, 7, 8]
+    v1 = [1, 1, 1, 0]
+    v2 = [2, 2, 2, 3]
+    kb1 = KnowledgeBase(vocab=nlp.vocab, entity_vector_length=4)
+    kb1.set_entities(["E0"], [1], [v])
+    assert kb1.get_entity_strings() == ["E0"]
+    kb1.set_entities(["E1", "E2"], [1, 9], [v1, v2])
+    assert set(kb1.get_entity_strings()) == {"E1", "E2"}
+    assert kb1.get_vector("E1") == v1
+    assert kb1.get_vector("E2") == v2
+    with make_tempdir() as d:
+        kb1.to_disk(d / "kb")
+        kb2 = KnowledgeBase(vocab=nlp.vocab, entity_vector_length=4)
+        kb2.from_disk(d / "kb")
+        assert set(kb2.get_entity_strings()) == {"E1", "E2"}
+        assert kb2.get_vector("E1") == v1
+        assert kb2.get_vector("E2") == v2
+
+
 def test_kb_serialize_vocab(nlp):
     """Test serialization of the KB and custom strings"""
     entity = "MyFunnyID"