diff --git a/spacy_llm/tasks/rel/task.py b/spacy_llm/tasks/rel/task.py
index fe9f6e4e..87f90622 100644
--- a/spacy_llm/tasks/rel/task.py
+++ b/spacy_llm/tasks/rel/task.py
@@ -71,7 +71,9 @@ def _preannotate(doc: Union[Doc, RELExample]) -> str:
         for i, ent in enumerate(doc.ents):
             end = ent.end_char
             before, after = text[: end + offset], text[end + offset :]
-            annotation = f"[ENT{i}:{ent.label}]"
+            annotation = (
+                f"[ENT{i}:{ent.label if isinstance(doc, RELExample) else ent.label_}]"
+            )
             offset += len(annotation)
             text = f"{before}{annotation}{after}"
 
diff --git a/spacy_llm/tests/tasks/test_rel.py b/spacy_llm/tests/tasks/test_rel.py
index eb685f2e..e4c110ae 100644
--- a/spacy_llm/tests/tasks/test_rel.py
+++ b/spacy_llm/tests/tasks/test_rel.py
@@ -266,3 +266,23 @@ def test_incorrect_indexing():
         )
         == 0
     )
+
+
+@pytest.mark.external
+@pytest.mark.skipif(has_openai_key is False, reason="OpenAI API key not available")
+def test_labels_in_prompt(request: FixtureRequest):
+    """See https://github.com/explosion/spacy-llm/issues/366."""
+    config = Config().from_str(request.getfixturevalue("zeroshot_cfg_string"))
+    config["components"].pop("ner")
+    config.pop("initialize")
+    config["nlp"]["pipeline"] = ["llm"]
+    config["components"]["llm"]["task"]["labels"] = ["A", "B", "C"]
+    nlp = assemble_from_config(config)
+
+    doc = Doc(get_lang_class("en")().vocab, words=["Well", "hello", "there"])
+    doc.ents = [Span(doc, 0, 1, "A"), Span(doc, 1, 2, "B"), Span(doc, 2, 3, "C")]
+
+    assert (
+        "Well[ENT0:A] hello[ENT1:B] there[ENT2:C]"
+        in list(nlp.get_pipe("llm")._task.generate_prompts([doc]))[0]
+    )