diff --git a/hole-punch-interop/impl/python/v0.4.0/Dockerfile b/hole-punch-interop/impl/python/v0.4.0/Dockerfile
new file mode 100644
index 000000000..30ed861a5
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/Dockerfile
@@ -0,0 +1,23 @@
+FROM python:3.12-slim
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y git build-essential iptables libgmp-dev && rm -rf /var/lib/apt/lists/*
+
+# Upgrade pip and build tools
+RUN python -m pip install --upgrade pip setuptools wheel
+
+WORKDIR /app
+
+# Copy only pyproject.toml first to leverage Docker cache
+COPY pyproject.toml .
+RUN pip install --no-cache-dir -e .
+
+# Copy rest of the code
+COPY hole_punch.py .
+
+# Startup script for iptables + python app
+COPY start.sh /start.sh
+RUN chmod +x /start.sh
+ENTRYPOINT ["/start.sh"]
+
+VOLUME /results
diff --git a/hole-punch-interop/impl/python/v0.4.0/Makefile b/hole-punch-interop/impl/python/v0.4.0/Makefile
new file mode 100644
index 000000000..49643f032
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/Makefile
@@ -0,0 +1,16 @@
+image_name := python-v0.4.0
+
+.PHONY: all build clean
+
+all: image.json
+
+image.json: Dockerfile
+	IMAGE_NAME=${image_name} ../../../dockerBuildWrapper.sh .
+	docker image inspect ${image_name} -f "{{.Id}}" | \
+		xargs -I {} echo "{\"imageID\": \"{}\"}" > $@
+
+build: image.json
+
+clean:
+	rm -f image.json
+	docker rmi ${image_name} || true
\ No newline at end of file
diff --git a/hole-punch-interop/impl/python/v0.4.0/README.md b/hole-punch-interop/impl/python/v0.4.0/README.md
new file mode 100644
index 000000000..837f0d5ca
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/README.md
@@ -0,0 +1,12 @@
+# Python Hole-Punch Interop Test (py-libp2p v0.4.0)
+
+Implements DCUtR hole punching for py-libp2p v0.4.0.
+
+## Local Testing
+
+```bash
+cd hole-punch-interop/impl/python/v0.4.0
+python3 -m venv .venv
+source .venv/bin/activate
+pip install -e .
+make build
\ No newline at end of file
diff --git a/hole-punch-interop/impl/python/v0.4.0/__init__.py b/hole-punch-interop/impl/python/v0.4.0/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/hole-punch-interop/impl/python/v0.4.0/hole_punch.py b/hole-punch-interop/impl/python/v0.4.0/hole_punch.py
new file mode 100644
index 000000000..28a6156b6
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/hole_punch.py
@@ -0,0 +1,171 @@
+#!/usr/bin/env python3
+"""
+Hole-Punch Interop Test for py-libp2p v0.3.x
+Supports initiator & receiver roles.
+Writes to /results/results.csv
+"""
+
+import asyncio
+import json
+import logging
+import os
+import time
+from typing import Sequence, Literal
+
+from libp2p import new_host
+from libp2p.abc import IHost
+from libp2p.crypto.secp256k1 import create_new_key_pair
+from libp2p.peer.id import ID
+from libp2p.peer.peerinfo import info_from_p2p_addr
+from libp2p.transport.upgrader import TransportUpgrader
+from multiaddr import Multiaddr
+from libp2p.custom_types import (
+    TProtocol,
+)
+
+DCUTR_PROTOCOL = TProtocol("/libp2p/dcutr/1.0.0")
+PING_PROTOCOL = TProtocol("/test/ping/1.0.0")
+
+logging.basicConfig(
+    level=logging.INFO,
+    format="%(asctime)s | %(levelname)s | %(message)s",
+    datefmt="%H:%M:%S",
+)
+log = logging.getLogger("hole-punch")
+
+async def create_host(listen_addrs: Sequence[Multiaddr] | None = None) -> IHost:
+    key_pair = create_new_key_pair()
+
+    host: IHost = new_host(
+        key_pair=key_pair,
+        muxer_preference="MPLEX",   
+        listen_addrs=listen_addrs or [Multiaddr("/ip4/0.0.0.0/tcp/0")]
+    )
+    return host
+
+async def main() -> None:
+    mode = os.environ["MODE"].lower()
+    relay_addr_str = os.environ["RELAY_MULTIADDR"]
+    target_id_str = os.environ["TARGET_ID"]
+
+    # Create and start listening
+    host = await create_host()
+    addrs = host.get_addrs()
+    log.info(f"Listening on: {[str(a) for a in addrs]}")
+
+    # Connect to the relay
+    relay_ma = Multiaddr(relay_addr_str)
+    relay_info = info_from_p2p_addr(relay_ma)
+    await host.connect(relay_info)
+    log.info(f"Connected to relay: {relay_ma}")
+
+    # Connect to the *target* via the relay (control channel)
+    target_id = ID(target_id_str.encode())
+    relayed_target_ma = Multiaddr(f"{relay_addr_str}/p2p-circuit/p2p/{target_id}")
+    target_info = info_from_p2p_addr(relayed_target_ma)
+    await host.connect(target_info)
+    log.info(f"Connected to target via relay: {relayed_target_ma}")
+
+    if mode == "initiator":
+        await initiator_role(host, target_id)
+    else:
+        await receiver_role(host)
+
+async def initiator_role(host: IHost, target_id: ID) -> None:
+    stream = await host.new_stream(target_id, [DCUTR_PROTOCOL])
+
+    # Send CONNECT
+    my_addrs = [str(a) for a in host.get_addrs()]
+    await stream.write(json.dumps({"type": "CONNECT", "addrs": my_addrs}).encode())
+    log.info(f"Sent CONNECT with {len(my_addrs)} addrs")
+
+    # Receive SYNC
+    try:
+        raw = await asyncio.wait_for(stream.read(4096), timeout=15)
+        msg = json.loads(raw.decode())
+        if msg.get("type") != "SYNC":
+            raise ValueError("expected SYNC")
+        peer_addrs = msg.get("addrs", [])
+        log.info(f"Received SYNC with {len(peer_addrs)} addrs")
+    except Exception as e:
+        log.error(f"SYNC failed: {e}")
+        await write_result("failure")
+        await stream.close()
+        return
+    finally:
+        await stream.close()
+
+    # Direct dial the first address
+    if peer_addrs:
+        try:
+            direct_ma = Multiaddr(peer_addrs[0])
+            direct_info = info_from_p2p_addr(direct_ma)
+            await host.connect(direct_info)
+            log.info(f"Direct connection SUCCESS → {direct_ma}")
+        except Exception as e:
+            log.warning(f"Direct dial failed: {e}")
+            await write_result("failure")
+            return
+
+    # Ping test
+    try:
+        ping = await host.new_stream(target_id, [PING_PROTOCOL])
+        start = time.time()
+        await ping.write(b"ping")
+        resp = await asyncio.wait_for(ping.read(4), timeout=5)
+        rtt = (time.time() - start) * 1000
+        if resp == b"pong":
+            log.info(f"Ping RTT: {rtt:.1f} ms → SUCCESS")
+            await write_result("success")
+        else:
+            log.error("Ping failed – bad response")
+            await write_result("failure")
+        await ping.close()
+    except Exception as e:
+        log.error(f"Ping failed: {e}")
+        await write_result("failure")
+
+async def receiver_role(host: IHost) -> None:
+    async def dcutr_handler(stream):
+        try:
+            data = await stream.read(4096)
+            msg = json.loads(data.decode())
+            if msg.get("type") != "CONNECT":
+                return
+
+            my_addrs = [str(a) for a in host.get_addrs()]
+            await stream.write(json.dumps({"type": "SYNC", "addrs": my_addrs}).encode())
+            log.info(f"Sent SYNC with {len(my_addrs)} addrs")
+
+            if msg.get("addrs"):
+                addr = Multiaddr(msg["addrs"][0])
+                info = info_from_p2p_addr(addr)
+                asyncio.create_task(host.connect(info))
+        except Exception as e:
+            log.error(f"DCUtR handler error: {e}")
+        finally:
+            await stream.close()
+
+    async def ping_handler(stream):
+        try:
+            data = await stream.read(4)
+            if data == b"ping":
+                await stream.write(b"pong")
+        finally:
+            await stream.close()
+
+    host.set_stream_handler(DCUTR_PROTOCOL, dcutr_handler)
+    host.set_stream_handler(PING_PROTOCOL, ping_handler)
+    log.info("Receiver ready – awaiting initiator…")
+    await asyncio.Event().wait()  
+
+async def write_result(result: str) -> None:
+    impl = os.environ.get("TARGET_IMPL", "go")
+    os.makedirs("/results", exist_ok=True)
+    line = f'"python-v0.3.x x {impl}-v0.42 (dcutr,tcp,noise)",{result}\n'
+    with open("/results/results.csv", "a") as f:
+        f.write(line)
+    log.info(f"RESULT: {result.upper()}")
+
+if __name__ == "__main__":
+    asyncio.run(main())
\ No newline at end of file
diff --git a/hole-punch-interop/impl/python/v0.4.0/pyproject.toml b/hole-punch-interop/impl/python/v0.4.0/pyproject.toml
new file mode 100644
index 000000000..2138187ce
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/pyproject.toml
@@ -0,0 +1,10 @@
+[build-system]
+requires = ["setuptools", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "hole-punch-python"
+version = "0.4.0"
+dependencies = [
+  "libp2p @ git+https://github.com/libp2p/py-libp2p.git@v0.4.0"
+]
\ No newline at end of file
diff --git a/hole-punch-interop/impl/python/v0.4.0/start.sh b/hole-punch-interop/impl/python/v0.4.0/start.sh
new file mode 100644
index 000000000..e7a332156
--- /dev/null
+++ b/hole-punch-interop/impl/python/v0.4.0/start.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+# Setup NAT
+iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
+# Start Python app
+exec python hole_punch.py
diff --git a/hole-punch-interop/versions.ts b/hole-punch-interop/versions.ts
index 7f4a0f88b..fc8172b0a 100644
--- a/hole-punch-interop/versions.ts
+++ b/hole-punch-interop/versions.ts
@@ -19,9 +19,9 @@ function canonicalImagePath(id: string): string {
     // Drop the patch version
     const [major, minor, patch] = version.split(".")
     let versionFolder = `v${major}.${minor}`
-    if (major === "0" && minor === "0") {
-        // We're still in the 0.0.x phase, so we use the patch version
-        versionFolder = `v0.0.${patch}`
+    if (major === "0" && patch !== undefined) {
+        // We're still in the 0.x.y phase, so we use the full version
+        versionFolder = `v${major}.${minor}.${patch}`
     }
     // Read the image ID from the JSON file on the filesystem
     return `./impl/${impl}/${versionFolder}/image.json`
diff --git a/hole-punch-interop/versionsInput.json b/hole-punch-interop/versionsInput.json
index 7299a87f7..0533cf95d 100644
--- a/hole-punch-interop/versionsInput.json
+++ b/hole-punch-interop/versionsInput.json
@@ -4,5 +4,11 @@
     "transports": ["tcp", "quic"],
     "secureChannels": [],
     "muxers": []
+  },
+  {
+    "id": "python-v0.4.0",
+    "transports": ["tcp", "quic"],
+    "secureChannels": [],
+    "muxers": []
   }
 ]