diff --git a/contrib/pyln-client/pyln/client/lightning.py b/contrib/pyln-client/pyln/client/lightning.py
index 096809e38..e3545d9a9 100644
--- a/contrib/pyln-client/pyln/client/lightning.py
+++ b/contrib/pyln-client/pyln/client/lightning.py
@@ -1,5 +1,6 @@
 from decimal import Decimal
 from math import floor, log10
+from typing import Optional, Union
 import json
 import logging
 import os
@@ -23,9 +24,12 @@ def monkey_patch_json(patch=True):
 
 
 class RpcError(ValueError):
-    def __init__(self, method, payload, error):
-        super(ValueError, self).__init__("RPC call failed: method: {}, payload: {}, error: {}"
-                                         .format(method, payload, error))
+    def __init__(self, method: str, payload: dict, error: str):
+        super(ValueError, self).__init__(
+            "RPC call failed: method: {}, payload: {}, error: {}".format(
+                method, payload, error
+            )
+        )
 
         self.method = method
         self.payload = payload
@@ -36,10 +40,10 @@ class Millisatoshi:
     """
     A subtype to represent thousandths of a satoshi.
 
-    Many JSON API fields are expressed in millisatoshis: these automatically get
-    turned into Millisatoshi types. Converts to and from int.
+    Many JSON API fields are expressed in millisatoshis: these automatically
+    get turned into Millisatoshi types. Converts to and from int.
     """
-    def __init__(self, v):
+    def __init__(self, v: Union[int, str, Decimal]):
         """
         Takes either a string ending in 'msat', 'sat', 'btc' or an integer.
         """
@@ -47,43 +51,50 @@ class Millisatoshi:
             if v.endswith("msat"):
                 self.millisatoshis = int(v[0:-4])
             elif v.endswith("sat"):
-                self.millisatoshis = Decimal(v[0:-3]) * 1000
+                self.millisatoshis = int(v[0:-3]) * 1000
             elif v.endswith("btc"):
-                self.millisatoshis = Decimal(v[0:-3]) * 1000 * 10**8
+                self.millisatoshis = int(v[0:-3]) * 1000 * 10**8
             else:
-                raise TypeError("Millisatoshi must be string with msat/sat/btc suffix or int")
+                raise TypeError(
+                    "Millisatoshi must be string with msat/sat/btc suffix or"
+                    " int"
+                )
             if self.millisatoshis != int(self.millisatoshis):
                 raise ValueError("Millisatoshi must be a whole number")
             self.millisatoshis = int(self.millisatoshis)
+
         elif isinstance(v, Millisatoshi):
             self.millisatoshis = v.millisatoshis
+
         elif int(v) == v:
             self.millisatoshis = int(v)
         else:
-            raise TypeError("Millisatoshi must be string with msat/sat/btc suffix or int")
+            raise TypeError(
+                "Millisatoshi must be string with msat/sat/btc suffix or int"
+            )
 
         if self.millisatoshis < 0:
             raise ValueError("Millisatoshi must be >= 0")
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         """
         Appends the 'msat' as expected for this type.
         """
         return str(self.millisatoshis) + "msat"
 
-    def to_satoshi(self):
+    def to_satoshi(self) -> Decimal:
         """
         Return a Decimal representing the number of satoshis.
         """
         return Decimal(self.millisatoshis) / 1000
 
-    def to_btc(self):
+    def to_btc(self) -> Decimal:
         """
         Return a Decimal representing the number of bitcoin.
         """
         return Decimal(self.millisatoshis) / 1000 / 10**8
 
-    def to_satoshi_str(self):
+    def to_satoshi_str(self) -> str:
         """
         Return a string of form 1234sat or 1234.567sat.
         """
@@ -92,7 +103,7 @@ class Millisatoshi:
         else:
             return '{:.0f}sat'.format(self.to_satoshi())
 
-    def to_btc_str(self):
+    def to_btc_str(self) -> str:
         """
         Return a string of form 12.34567890btc or 12.34567890123btc.
         """
@@ -101,13 +112,14 @@ class Millisatoshi:
         else:
             return '{:.8f}btc'.format(self.to_btc())
 
-    def to_approx_str(self, digits: int = 3):
+    def to_approx_str(self, digits: int = 3) -> str:
         """Returns the shortmost string using common units representation.
 
         Rounds to significant `digits`. Default: 3
         """
-        round_to_n = lambda x, n: round(x, -int(floor(log10(x))) + (n - 1))
-        result = None
+        def round_to_n(x: int, n: int) -> float:
+            return round(x, -int(floor(log10(x))) + (n - 1))
+        result = self.to_satoshi_str()
 
         # we try to increase digits to check if we did loose out on precision
         # without gaining a shorter string, since this is a rarely used UI
@@ -132,46 +144,51 @@ class Millisatoshi:
             else:
                 return result
 
-    def to_json(self):
+    def to_json(self) -> str:
         return self.__repr__()
 
-    def __int__(self):
+    def __int__(self) -> int:
         return self.millisatoshis
 
-    def __lt__(self, other):
+    def __lt__(self, other: 'Millisatoshi') -> bool:
         return self.millisatoshis < other.millisatoshis
 
-    def __le__(self, other):
+    def __le__(self, other: 'Millisatoshi') -> bool:
         return self.millisatoshis <= other.millisatoshis
 
-    def __eq__(self, other):
-        return self.millisatoshis == other.millisatoshis
+    def __eq__(self, other: object) -> bool:
+        if isinstance(other, Millisatoshi):
+            return self.millisatoshis == other.millisatoshis
+        elif isinstance(other, int):
+            return self.millisatoshis == other
+        else:
+            return False
 
-    def __gt__(self, other):
+    def __gt__(self, other: 'Millisatoshi') -> bool:
         return self.millisatoshis > other.millisatoshis
 
-    def __ge__(self, other):
+    def __ge__(self, other: 'Millisatoshi') -> bool:
         return self.millisatoshis >= other.millisatoshis
 
-    def __add__(self, other):
+    def __add__(self, other: 'Millisatoshi') -> 'Millisatoshi':
         return Millisatoshi(int(self) + int(other))
 
-    def __sub__(self, other):
+    def __sub__(self, other: 'Millisatoshi') -> 'Millisatoshi':
         return Millisatoshi(int(self) - int(other))
 
-    def __mul__(self, other):
-        return Millisatoshi(int(int(self) * other))
+    def __mul__(self, other: int) -> 'Millisatoshi':
+        return Millisatoshi(self.millisatoshis * other)
 
-    def __truediv__(self, other):
-        return Millisatoshi(int(int(self) / other))
+    def __truediv__(self, other: Union[int, float]) -> 'Millisatoshi':
+        return Millisatoshi(int(self.millisatoshis / other))
 
-    def __floordiv__(self, other):
-        return Millisatoshi(int(self) // other)
+    def __floordiv__(self, other: Union[int, float]) -> 'Millisatoshi':
+        return Millisatoshi(int(self.millisatoshis // float(other)))
 
-    def __mod__(self, other):
-        return Millisatoshi(int(self) % other)
+    def __mod__(self, other: Union[float, int]) -> 'Millisatoshi':
+        return Millisatoshi(int(self.millisatoshis % other))
 
-    def __radd__(self, other):
+    def __radd__(self, other: 'Millisatoshi') -> 'Millisatoshi':
         return Millisatoshi(int(self) + int(other))
 
 
@@ -188,17 +205,17 @@ class UnixSocket(object):
 
     """
 
-    def __init__(self, path):
+    def __init__(self, path: str):
         self.path = path
-        self.sock = None
+        self.sock: Optional[socket.SocketType] = None
         self.connect()
 
-    def connect(self):
+    def connect(self) -> None:
         try:
             self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-            return self.sock.connect(self.path)
+            self.sock.connect(self.path)
         except OSError as e:
-            self.sock.close()
+            self.close()
 
             if (e.args[0] == "AF_UNIX path too long" and os.uname()[0] == "Linux"):
                 # If this is a Linux system we may be able to work around this
@@ -216,29 +233,29 @@ class UnixSocket(object):
                 dirfd = os.open(dirname, os.O_DIRECTORY | os.O_RDONLY)
                 short_path = "/proc/self/fd/%d/%s" % (dirfd, basename)
                 self.sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-                return self.sock.connect(short_path)
+                self.sock.connect(short_path)
             else:
                 # There is no good way to recover from this.
                 raise
 
-    def close(self):
+    def close(self) -> None:
         if self.sock is not None:
             self.sock.close()
         self.sock = None
 
-    def sendall(self, b):
+    def sendall(self, b: bytes) -> None:
         if self.sock is None:
             raise socket.error("not connected")
 
         self.sock.sendall(b)
 
-    def recv(self, length):
+    def recv(self, length: int) -> bytes:
         if self.sock is None:
             raise socket.error("not connected")
 
         return self.sock.recv(length)
 
-    def __del__(self):
+    def __del__(self) -> None:
         self.close()