diff --git a/synapse/storage/keys.py b/synapse/storage/keys.py
index 0540c2b0b164..0f13b61da897 100644
--- a/synapse/storage/keys.py
+++ b/synapse/storage/keys.py
@@ -17,6 +17,7 @@
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 
 from twisted.internet import defer
+import six
 
 import OpenSSL
 from signedjson.key import decode_verify_key_bytes
@@ -26,6 +27,13 @@
 
 logger = logging.getLogger(__name__)
 
+# py2 sqlite has buffer hardcoded as only binary type, so we must use it,
+# despite being deprecated and removed in favor of memoryview
+if six.PY2:
+    db_binary_type = buffer
+else:
+    db_binary_type = memoryview
+
 
 class KeyStore(SQLBaseStore):
     """Persistence for signature verification keys and tls X.509 certificates
@@ -72,7 +80,7 @@ def store_server_certificate(self, server_name, from_server, time_now_ms,
             values={
                 "from_server": from_server,
                 "ts_added_ms": time_now_ms,
-                "tls_certificate": buffer(tls_certificate_bytes),
+                "tls_certificate": db_binary_type(tls_certificate_bytes),
             },
             desc="store_server_certificate",
         )
@@ -135,7 +143,7 @@ def _txn(txn):
                 values={
                     "from_server": from_server,
                     "ts_added_ms": time_now_ms,
-                    "verify_key": buffer(verify_key.encode()),
+                    "verify_key": db_binary_type(verify_key.encode()),
                 },
             )
             txn.call_after(
@@ -172,7 +180,7 @@ def store_server_keys_json(self, server_name, key_id, from_server,
                 "from_server": from_server,
                 "ts_added_ms": ts_now_ms,
                 "ts_valid_until_ms": ts_expires_ms,
-                "key_json": buffer(key_json_bytes),
+                "key_json": db_binary_type(key_json_bytes),
             },
             desc="store_server_keys_json",
         )
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
index 9e6eaaa532e3..25922e5a9cd7 100644
--- a/synapse/storage/signatures.py
+++ b/synapse/storage/signatures.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 from twisted.internet import defer
+import six
 
 from ._base import SQLBaseStore
 
@@ -21,6 +22,13 @@
 from synapse.crypto.event_signing import compute_event_reference_hash
 from synapse.util.caches.descriptors import cached, cachedList
 
+# py2 sqlite has buffer hardcoded as only binary type, so we must use it,
+# despite being deprecated and removed in favor of memoryview
+if six.PY2:
+    db_binary_type = buffer
+else:
+    db_binary_type = memoryview
+
 
 class SignatureWorkerStore(SQLBaseStore):
     @cached()
@@ -56,7 +64,7 @@ def add_event_hashes(self, event_ids):
             for e_id, h in hashes.items()
         }
 
-        defer.returnValue(hashes.items())
+        defer.returnValue(list(hashes.items()))
 
     def _get_event_reference_hashes_txn(self, txn, event_id):
         """Get all the hashes for a given PDU.
@@ -91,7 +99,7 @@ def _store_event_reference_hashes_txn(self, txn, events):
             vals.append({
                 "event_id": event.event_id,
                 "algorithm": ref_alg,
-                "hash": buffer(ref_hash_bytes),
+                "hash": db_binary_type(ref_hash_bytes),
             })
 
         self._simple_insert_many_txn(
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index f825264ea9cc..e485d19b84d6 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -17,6 +17,7 @@
 from synapse.util.caches.descriptors import cached
 
 from twisted.internet import defer
+import six
 
 from canonicaljson import encode_canonical_json
 
@@ -25,6 +26,13 @@
 import logging
 import simplejson as json
 
+# py2 sqlite has buffer hardcoded as only binary type, so we must use it,
+# despite being deprecated and removed in favor of memoryview
+if six.PY2:
+    db_binary_type = buffer
+else:
+    db_binary_type = memoryview
+
 logger = logging.getLogger(__name__)
 
 
@@ -110,7 +118,7 @@ def set_received_txn_response(self, transaction_id, origin, code,
                 "transaction_id": transaction_id,
                 "origin": origin,
                 "response_code": code,
-                "response_json": buffer(encode_canonical_json(response_dict)),
+                "response_json": db_binary_type(encode_canonical_json(response_dict)),
                 "ts": self._clock.time_msec(),
             },
             or_ignore=True,