diff --git a/connectors/es/sink.py b/connectors/es/sink.py
index 52df8f59a..9bee7e7b2 100644
--- a/connectors/es/sink.py
+++ b/connectors/es/sink.py
@@ -545,7 +545,8 @@ async def get_docs(self, generator, skip_unchanged_documents=False):
                 if count % self.display_every == 0:
                     self._log_progress()
 
-                doc_id = doc["id"] = doc.pop("_id")
+                doc_id = doc.pop("_id")
+                doc["id"] = str(doc_id)
 
                 if self.basic_rule_engine and not self.basic_rule_engine.should_ingest(
                     doc
@@ -660,7 +661,8 @@ async def get_docs_incrementally(self, generator):
                 if count % self.display_every == 0:
                     self._log_progress()
 
-                doc_id = doc["id"] = doc.pop("_id")
+                doc_id = doc.pop("_id")
+                doc["id"] = str(doc_id)
 
                 if self.basic_rule_engine and not self.basic_rule_engine.should_ingest(
                     doc
@@ -737,7 +739,8 @@ async def get_access_control_docs(self, generator):
             if count % self.display_every == 0:
                 self._log_progress()
 
-            doc_id = doc["id"] = doc.pop("_id")
+            doc_id = doc.pop("_id")
+            doc["id"] = str(doc_id)
             doc_exists = doc_id in existing_ids
 
             if doc_exists:
diff --git a/tests/test_sink.py b/tests/test_sink.py
index c8f374f9c..98bba50f7 100644
--- a/tests/test_sink.py
+++ b/tests/test_sink.py
@@ -361,7 +361,8 @@ async def _dl(doit=True, timestamp=None):
 def index_operation(doc):
     # deepcopy as get_docs mutates docs
     doc_copy = deepcopy(doc)
-    doc_id = doc_copy["id"] = doc_copy.pop("_id")
+    doc_id = doc_copy.pop("_id")
+    doc_copy["id"] = str(doc_id)
 
     return {"_op_type": "index", "_index": INDEX, "_id": doc_id, "doc": doc_copy}
 
@@ -369,7 +370,8 @@ def index_operation(doc):
 def update_operation(doc):
     # deepcopy as get_docs mutates docs
     doc_copy = deepcopy(doc)
-    doc_id = doc_copy["id"] = doc_copy.pop("_id")
+    doc_id = doc_copy.pop("_id")
+    doc_copy["id"] = str(doc_id)
 
     return {"_op_type": "update", "_index": INDEX, "_id": doc_id, "doc": doc_copy}