diff --git a/spacy/tests/doc/test_add_entities.py b/spacy/tests/doc/test_add_entities.py
index 40aff8e31..615ab9e5b 100644
--- a/spacy/tests/doc/test_add_entities.py
+++ b/spacy/tests/doc/test_add_entities.py
@@ -29,10 +29,10 @@ def test_doc_add_entities_set_ents_iob(en_vocab):
     ner.begin_training(lambda: [_ner_example(ner)])
     ner(doc)
 
-    doc.ents = [(doc.vocab.strings["ANIMAL"], 3, 4)]
+    doc.ents = [("ANIMAL", 3, 4)]
     assert [w.ent_iob_ for w in doc] == ["O", "O", "O", "B"]
 
-    doc.ents = [(doc.vocab.strings["WORD"], 0, 2)]
+    doc.ents = [("WORD", 0, 2)]
     assert [w.ent_iob_ for w in doc] == ["B", "I", "O", "O"]
 
 
diff --git a/spacy/tests/doc/test_doc_api.py b/spacy/tests/doc/test_doc_api.py
index 892b65cf4..e5e72fe2a 100644
--- a/spacy/tests/doc/test_doc_api.py
+++ b/spacy/tests/doc/test_doc_api.py
@@ -534,4 +534,4 @@ def test_doc_ents_setter():
     vocab = Vocab()
     ents = [("HELLO", 0, 2), (vocab.strings.add("WORLD"), 3, 5)]
     doc = Doc(vocab, words=words, ents=ents)
-    assert [e.label_ for e in doc.ents] == ["HELLO", "WORLD"]
\ No newline at end of file
+    assert [e.label_ for e in doc.ents] == ["HELLO", "WORLD"]
diff --git a/spacy/tokens/doc.pyx b/spacy/tokens/doc.pyx
index 4bf6f0e5e..670c7440f 100644
--- a/spacy/tokens/doc.pyx
+++ b/spacy/tokens/doc.pyx
@@ -673,49 +673,16 @@ cdef class Doc:
             # TODO:
             # 1. Test basic data-driven ORTH gazetteer
             # 2. Test more nuanced date and currency regex
-            tokens_in_ents = {}
-            cdef attr_t entity_type
-            cdef attr_t kb_id
-            cdef int ent_start, ent_end, token_index
+            cdef attr_t entity_type, kb_id
+            cdef int ent_start, ent_end
+            ent_spans = []
             for ent_info in ents:
                 entity_type_, kb_id, ent_start, ent_end = get_entity_info(ent_info)
                 if isinstance(entity_type_, str):
                     self.vocab.strings.add(entity_type_)
-                entity_type = self.vocab.strings.as_int(entity_type_)
-                for token_index in range(ent_start, ent_end):
-                    if token_index in tokens_in_ents:
-                        raise ValueError(Errors.E103.format(
-                            span1=(tokens_in_ents[token_index][0],
-                                   tokens_in_ents[token_index][1],
-                                   self.vocab.strings[tokens_in_ents[token_index][2]]),
-                            span2=(ent_start, ent_end, self.vocab.strings[entity_type])))
-                    tokens_in_ents[token_index] = (ent_start, ent_end, entity_type, kb_id)
-            cdef int i
-            for i in range(self.length):
-                # default values
-                entity_type = 0
-                kb_id = 0
-
-                # Set ent_iob to Outside (2) by default
-                ent_iob = 2
-
-                # overwrite if the token was part of a specified entity
-                if i in tokens_in_ents.keys():
-                    ent_start, ent_end, entity_type, kb_id = tokens_in_ents[i]
-                    if entity_type is None or entity_type <= 0:
-                        # Only allow labelled spans
-                        print(i, ent_start, ent_end, entity_type)
-                        raise ValueError(Errors.E1013)
-                    elif ent_start == i:
-                        # Marking the start of an entity
-                        ent_iob = 3
-                    else:
-                        # Marking the inside of an entity
-                        ent_iob = 1
-
-                self.c[i].ent_type = entity_type
-                self.c[i].ent_kb_id = kb_id
-                self.c[i].ent_iob = ent_iob
+                span = Span(self, ent_start, ent_end, label=entity_type_, kb_id=kb_id)
+                ent_spans.append(span)
+            self.set_ents(ent_spans, default=SetEntsDefault.outside)
 
     def set_ents(self, entities, *, blocked=None, missing=None, outside=None, default=SetEntsDefault.outside):
         """Set entity annotation.
@@ -734,6 +701,9 @@ cdef class Doc:
         if default not in SetEntsDefault.values():
             raise ValueError(Errors.E1011.format(default=default, modes=", ".join(SetEntsDefault)))
 
+        # Ignore spans with missing labels
+        entities = [ent for ent in entities if ent.label > 0]
+
         if blocked is None:
             blocked = tuple()
         if missing is None:
@@ -742,6 +712,7 @@ cdef class Doc:
             outside = tuple()
 
         # Find all tokens covered by spans and check that none are overlapping
+        cdef int i
         seen_tokens = set()
         for span in itertools.chain.from_iterable([entities, blocked, missing, outside]):
             if not isinstance(span, Span):
@@ -761,6 +732,7 @@ cdef class Doc:
                 else:
                     self.c[i].ent_iob = 1
                 self.c[i].ent_type = span.label
+                self.c[i].ent_kb_id = span.kb_id
         for span in blocked:
             for i in range(span.start, span.end):
                 self.c[i].ent_iob = 3