diff --git a/tests/speculos/ethereum_client/plugin.py b/tests/speculos/ethereum_client/plugin.py
new file mode 100644
index 0000000..17a82f4
--- /dev/null
+++ b/tests/speculos/ethereum_client/plugin.py
@@ -0,0 +1,40 @@
+from typing import Union
+
+from ethereum_client.utils import (read, read_uint, read_varint,
+                                      write_varint, UINT64_MAX)
+
+class Plugin:
+    def __init__(self, type: int, version: int, name: str, addr: Union[str, bytes], selector: int = -1, chainID: int = 1, keyID: int = 0, algorithm: int = 1, sign: bytes = b'') -> None:
+        self.type: int = type
+        self.version: int = version
+        self.name: bytes = bytes(name, 'UTF-8')
+        self.addr: bytes = bytes.fromhex(addr[2:]) if isinstance(addr, str) else addr
+        self.selector: int = selector
+        self.chainID: int = chainID
+        self.keyID: int = keyID
+        self.algorithm: int = algorithm
+        self.sign: bytes = sign
+
+    def serialize(self) -> bytes:
+        return b"".join([
+            self.type.to_bytes(1, byteorder="big"),
+
+            self.version.to_bytes(1, byteorder="big"),
+
+            write_varint(len(self.name)),
+            self.name,
+
+            self.addr,
+
+            b'' if self.selector == -1 else self.selector.to_bytes(4, byteorder="big"),
+
+            self.chainID.to_bytes(8, byteorder="big"),
+
+            self.keyID.to_bytes(1, byteorder="big"),
+
+            self.algorithm.to_bytes(1, byteorder="big"),
+
+            write_varint(len(self.sign)),
+            self.sign,
+
+        ])
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