diff --git a/libp2p/pubsub/pubsub.py b/libp2p/pubsub/pubsub.py
index ac08b41..0b4d605 100644
--- a/libp2p/pubsub/pubsub.py
+++ b/libp2p/pubsub/pubsub.py
@@ -543,7 +543,10 @@ class Pubsub:
             # i.e., check if `msg.key` matches `msg.from_id`
             msg_pubkey = deserialize_public_key(msg.key)
             if ID.from_pubkey(msg_pubkey) != msg.from_id:
-                logger.debug("Reject because signing key does not match sender ID for msg: %s", msg)
+                logger.debug(
+                    "Reject because signing key does not match sender ID for msg: %s",
+                    msg,
+                )
                 return
             # Validate the signature of the message
             # First, construct the original payload that's signed by 'msg.key'
@@ -556,9 +559,7 @@ class Pubsub:
             payload = (
                 PUBSUB_SIGNING_PREFIX.encode() + msg_without_key_sig.SerializeToString()
             )
-            if not signature_validator(
-                msg_pubkey, payload, msg.signature
-            ):
+            if not signature_validator(msg_pubkey, payload, msg.signature):
                 logger.debug("Signature validation failed for msg: %s", msg)
                 return
 
diff --git a/tests/pubsub/test_pubsub.py b/tests/pubsub/test_pubsub.py
index 8052926..01d8ba7 100644
--- a/tests/pubsub/test_pubsub.py
+++ b/tests/pubsub/test_pubsub.py
@@ -5,8 +5,8 @@ import pytest
 
 from libp2p.exceptions import ValidationError
 from libp2p.peer.id import ID
-from libp2p.pubsub.pubsub import PUBSUB_SIGNING_PREFIX
 from libp2p.pubsub.pb import rpc_pb2
+from libp2p.pubsub.pubsub import PUBSUB_SIGNING_PREFIX
 from libp2p.tools.pubsub.utils import make_pubsub_msg
 from libp2p.tools.utils import connect
 from libp2p.utils import encode_varint_prefixed
@@ -538,9 +538,7 @@ async def test_strict_signing_failed_validation(pubsubs_fsub, hosts, monkeypatch
         seqno=b"\x00" * 8,
     )
     priv_key = pubsubs_fsub[0].sign_key
-    signature = priv_key.sign(
-        PUBSUB_SIGNING_PREFIX.encode() + msg.SerializeToString()
-    )
+    signature = priv_key.sign(PUBSUB_SIGNING_PREFIX.encode() + msg.SerializeToString())
 
     event = asyncio.Event()
 
diff --git a/tests_interop/conftest.py b/tests_interop/conftest.py
index e75e519..8ae9769 100644
--- a/tests_interop/conftest.py
+++ b/tests_interop/conftest.py
@@ -76,7 +76,24 @@ def is_gossipsub():
 
 
 @pytest.fixture
-async def p2pds(num_p2pds, is_host_secure, is_gossipsub, unused_tcp_port_factory):
+def is_pubsub_signing():
+    return True
+
+
+@pytest.fixture
+def is_pubsub_signing_strict():
+    return True
+
+
+@pytest.fixture
+async def p2pds(
+    num_p2pds,
+    is_host_secure,
+    is_gossipsub,
+    unused_tcp_port_factory,
+    is_pubsub_signing,
+    is_pubsub_signing_strict,
+):
     p2pds: Union[Daemon, Exception] = await asyncio.gather(
         *[
             make_p2pd(
@@ -84,6 +101,8 @@ async def p2pds(num_p2pds, is_host_secure, is_gossipsub, unused_tcp_port_factory
                 unused_tcp_port_factory(),
                 is_host_secure,
                 is_gossipsub=is_gossipsub,
+                is_pubsub_signing=is_pubsub_signing,
+                is_pubsub_signing_strict=is_pubsub_signing_strict,
             )
             for _ in range(num_p2pds)
         ],
@@ -102,13 +121,14 @@ async def p2pds(num_p2pds, is_host_secure, is_gossipsub, unused_tcp_port_factory
 
 
 @pytest.fixture
-def pubsubs(num_hosts, hosts, is_gossipsub):
+def pubsubs(num_hosts, hosts, is_gossipsub, is_pubsub_signing_strict):
     if is_gossipsub:
         routers = GossipsubFactory.create_batch(num_hosts, **GOSSIPSUB_PARAMS._asdict())
     else:
         routers = FloodsubFactory.create_batch(num_hosts)
     _pubsubs = tuple(
-        PubsubFactory(host=host, router=router) for host, router in zip(hosts, routers)
+        PubsubFactory(host=host, router=router, strict_signing=is_pubsub_signing_strict)
+        for host, router in zip(hosts, routers)
     )
     yield _pubsubs
     # TODO: Clean up
diff --git a/tests_interop/test_pubsub.py b/tests_interop/test_pubsub.py
index 4e845d7..f67b47a 100644
--- a/tests_interop/test_pubsub.py
+++ b/tests_interop/test_pubsub.py
@@ -55,6 +55,9 @@ def validate_pubsub_msg(msg: rpc_pb2.Message, data: bytes, from_peer_id: ID) ->
     assert msg.data == data and msg.from_id == from_peer_id
 
 
+@pytest.mark.parametrize(
+    "is_pubsub_signing, is_pubsub_signing_strict", ((True, True), (False, False))
+)
 @pytest.mark.parametrize("is_gossipsub", (True, False))
 @pytest.mark.parametrize("num_hosts, num_p2pds", ((1, 2),))
 @pytest.mark.asyncio