diff --git a/baudot/__init__.py b/baudot/__init__.py
index fef9753..de8c88f 100644
--- a/baudot/__init__.py
+++ b/baudot/__init__.py
@@ -1,6 +1,12 @@
-
 """
 Baudot – Tools for handling stateful 5-bit encoding
 """
 
-from .core import encode, encode_str, decode, decode_to_str
+from .core import decode, decode_to_str, encode, encode_str
+
+__all__ = [
+    "encode",
+    "encode_str",
+    "decode",
+    "decode_to_str",
+]
diff --git a/baudot/codecs/__init__.py b/baudot/codecs/__init__.py
index ce31756..2bea9f3 100644
--- a/baudot/codecs/__init__.py
+++ b/baudot/codecs/__init__.py
@@ -1,9 +1,18 @@
-
 """
 Codecs are the tools used to convert encoded-data (5-bit digits)
 into Unicode characters and back.
 """
 
-from .core import BaudotCodec, SimpleTabledCodec, Shift
+from .core import BaudotCodec, Shift, SimpleTabledCodec
 from .ita1_baudot import ITA1_CONTINENTAL, ITA1_UK
 from .ita2_baudot_murray import ITA2_STANDARD, ITA2_US
+
+__all__ = [
+    "BaudotCodec",
+    "SimpleTabledCodec",
+    "Shift",
+    "ITA1_CONTINENTAL",
+    "ITA1_UK",
+    "ITA2_STANDARD",
+    "ITA2_US",
+]
diff --git a/baudot/codecs/core.py b/baudot/codecs/core.py
index edfad87..8111983 100644
--- a/baudot/codecs/core.py
+++ b/baudot/codecs/core.py
@@ -28,13 +28,17 @@ class BaudotCodec(ABC):
     """
 
     @abstractmethod
-    def encode(self, value: Value, state: Shift) -> Tuple[int, Shift]:
+    def encode(
+        self,
+        value: Value,
+        state: Optional[Shift]
+    ) -> Tuple[int, Optional[Shift]]:
         """
         Abstract method for encoding a single character or state shift
         """
 
     @abstractmethod
-    def decode(self, code: int, state: Shift) -> Union[str, Shift]:
+    def decode(self, code: int, state: Optional[Shift]) -> Value:
         """
         Abstract method for decoding a single code.
         """
@@ -71,7 +75,11 @@ def __init__(self, name: str, tables: Dict[Shift, Table]):
         self.encoding_any: Dict[Value, int] = enc_any
         self.encoding_others: Dict[Value, Set[Tuple[int, Shift]]] = enc_others
 
-    def encode(self, value: Value, state: Shift) -> Tuple[int, Shift]:
+    def encode(
+        self,
+        value: Value,
+        state: Optional[Shift]
+    ) -> Tuple[int, Optional[Shift]]:
         """
         Get the code of the given character of Shift for this codec.
 
@@ -134,7 +142,7 @@ def decode(self, code: int, state: Optional[Shift]) -> Value:
         return self.decoding_table[state][code]
 
 
-def _verify_tables(tables: Dict[Shift, Table]):
+def _verify_tables(tables: Dict[Shift, Table]) -> None:
     """
     Function for verifying that a given input table is correct
     """
@@ -155,7 +163,13 @@ def _verify_tables(tables: Dict[Shift, Table]):
         raise IncoherentTable("Shifts in the tables don't match their keys")
 
 
-def _make_simple_encoding_table(tables: Dict[Shift, Table]):
+def _make_simple_encoding_table(
+        tables: Dict[Shift, Table]
+    ) -> Tuple[
+        Dict[Value, Tuple[int, Shift]],
+        Dict[Value, int],
+        Dict[Value, Set[Tuple[int, Shift]]],
+    ]:
     """
     Generates the encoding tables by reversing the decoding table
     """
diff --git a/baudot/codecs/ita1_baudot.py b/baudot/codecs/ita1_baudot.py
index 4bff746..170841d 100644
--- a/baudot/codecs/ita1_baudot.py
+++ b/baudot/codecs/ita1_baudot.py
@@ -2,13 +2,19 @@
 Codec definitions for first-generation Baudot codes (a.k.a. ITA1)
 """
 # pylint: disable=invalid-name
+from __future__ import annotations
+
+from typing import Dict, List, TYPE_CHECKING
 
 from .core import Shift, SimpleTabledCodec
 
+if TYPE_CHECKING:
+    from .core import Value
+
 Figures = Shift('Figures')
 Letters = Shift('Letters')
 
-CONTINENTAL_TABLE = {
+CONTINENTAL_TABLE: Dict[Shift, List[Value]] = {
     Letters: [
         ' ', 'A', 'E', 'É', 'Y', 'U', 'I', 'O',
         Figures, 'J', 'G', 'H', 'B', 'C', 'F', 'D',
@@ -23,7 +29,7 @@
     ],
 }
 
-UK_TABLE = {
+UK_TABLE: Dict[Shift, List[Value]] = {
     Letters: [
         ' ', 'A', 'E', '/', 'Y', 'U', 'I', 'O',
         Figures, 'J', 'G', 'H', 'B', 'C', 'F', 'D',
diff --git a/baudot/codecs/ita2_baudot_murray.py b/baudot/codecs/ita2_baudot_murray.py
index db8cc99..b9112cd 100644
--- a/baudot/codecs/ita2_baudot_murray.py
+++ b/baudot/codecs/ita2_baudot_murray.py
@@ -3,13 +3,19 @@
 (a.k.a. Baudot-Murray or ITA2)
 """
 # pylint: disable=invalid-name
+from __future__ import annotations
+
+from typing import Dict, List, TYPE_CHECKING
 
 from .core import Shift, SimpleTabledCodec
 
+if TYPE_CHECKING:
+    from .core import Value
+
 Letters = Shift('Letters')
 Figures = Shift('Figures')
 
-STANDARD_TABLE = {
+STANDARD_TABLE: Dict[Shift, List[Value]] = {
     Letters: [
         '\x00', 'E', '\n', 'A', ' ', 'S', 'I', 'U',
         '\r', 'D', 'R', 'J', 'N', 'F', 'C', 'K',
@@ -24,7 +30,7 @@
     ],
 }
 
-US_TABLE = {
+US_TABLE: Dict[Shift, List[Value]] = {
     Letters: STANDARD_TABLE[Letters].copy(),
     Figures: [
         '\x00', '3', '\n', '-', ' ', '\x07', '8', '7',
diff --git a/baudot/core.py b/baudot/core.py
index c792bc3..a85d11d 100644
--- a/baudot/core.py
+++ b/baudot/core.py
@@ -9,7 +9,7 @@
 from .codecs import BaudotCodec, Shift
 
 
-def encode(stream: TextIOBase, codec: BaudotCodec, writer: BaudotWriter):
+def encode(stream: TextIOBase, codec: BaudotCodec, writer: BaudotWriter) -> None:
     """
     Encode unicode characters from an input stream to an output writer,
     using the given codec.
@@ -30,6 +30,7 @@ def encode(stream: TextIOBase, codec: BaudotCodec, writer: BaudotWriter):
         buffer.append(code)
 
         if new_state != state:
+            assert new_state is not None
             state_code, _ = codec.encode(new_state, None)
             buffer.append(state_code)
             state = new_state
@@ -38,7 +39,7 @@ def encode(stream: TextIOBase, codec: BaudotCodec, writer: BaudotWriter):
             writer.write(buffer.pop(-1))
 
 
-def encode_str(chars: str, codec: BaudotCodec, writer: BaudotWriter):
+def encode_str(chars: str, codec: BaudotCodec, writer: BaudotWriter) -> None:
     """
     Encode unicode characters from an input string to an output writer,
     using the given codec.
@@ -51,7 +52,7 @@ def encode_str(chars: str, codec: BaudotCodec, writer: BaudotWriter):
         encode(stream, codec, writer)
 
 
-def decode(reader: BaudotReader, codec: BaudotCodec, stream: TextIOBase):
+def decode(reader: BaudotReader, codec: BaudotCodec, stream: TextIOBase) -> None:
     """
     Decode a baudot code stream from a reader to a unicode stream,
     using a given codec.
diff --git a/baudot/handlers/__init__.py b/baudot/handlers/__init__.py
index dc03f80..eec777a 100644
--- a/baudot/handlers/__init__.py
+++ b/baudot/handlers/__init__.py
@@ -1,9 +1,18 @@
-
 """
 The handlers are interfaces to read and write 5-bit data
 from a variety of formats.
 """
 
-from .core import BaudotWriter, BaudotReader
-from .tape import TapeReader, TapeWriter, TapeConfig
+from .core import BaudotReader, BaudotWriter
 from .hexbytes import HexBytesReader, HexBytesWriter
+from .tape import TapeConfig, TapeReader, TapeWriter
+
+__all__ = [
+    "BaudotWriter",
+    "BaudotReader",
+    "TapeReader",
+    "TapeWriter",
+    "TapeConfig",
+    "HexBytesReader",
+    "HexBytesWriter",
+]
diff --git a/baudot/handlers/core.py b/baudot/handlers/core.py
index 09e3695..7242e60 100644
--- a/baudot/handlers/core.py
+++ b/baudot/handlers/core.py
@@ -1,18 +1,23 @@
 """
 Core utilities for Baudot input/output handlers
 """
+from __future__ import annotations
 
 from abc import ABC, abstractmethod
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from collections.abc import Iterator
 
 
 class BaudotReader(ABC):
     """Abstract Base Class for a reader"""
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[int]:
         return self
 
     @abstractmethod
-    def __next__(self):
+    def __next__(self) -> int:
         pass
 
 
@@ -20,5 +25,5 @@ class BaudotWriter(ABC):
     """Abstract Base Class for a writer"""
 
     @abstractmethod
-    def write(self, code: int):
+    def write(self, code: int) -> None:
         """Write a single code to the output"""
diff --git a/baudot/handlers/hexbytes.py b/baudot/handlers/hexbytes.py
index be3bffd..2c06636 100644
--- a/baudot/handlers/hexbytes.py
+++ b/baudot/handlers/hexbytes.py
@@ -16,7 +16,7 @@ class HexBytesReader(BaudotReader):
     def __init__(self, stream: BufferedIOBase):
         self.stream = stream
 
-    def __next__(self):
+    def __next__(self) -> int:
         hex_byte = self.stream.read(2)
         if not hex_byte:
             raise StopIteration()
@@ -38,7 +38,7 @@ class HexBytesWriter(BaudotWriter):
     def __init__(self, stream: BufferedIOBase):
         self.stream = stream
 
-    def write(self, code: int):
+    def write(self, code: int) -> None:
         """Writes a code as an hexadecimal value"""
         if not 0 <= code < 32:
             raise WriteError('Invalid 5-bit character code')
diff --git a/baudot/handlers/tape.py b/baudot/handlers/tape.py
index 87e104e..3696bba 100644
--- a/baudot/handlers/tape.py
+++ b/baudot/handlers/tape.py
@@ -61,7 +61,7 @@ def __init__(self, stream: TextIOBase, config: TapeConfig = DEFAULT_TAPE):
         self.stream = stream
         self.config = config
 
-    def write(self, code: int):
+    def write(self, code: int) -> None:
         """Writes a code to tape"""
         if not 0 <= code < 32:
             raise WriteError('Invalid 5-bit character code')
diff --git a/baudot/py.typed b/baudot/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..2f38968
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,10 @@
+[tool.mypy]
+files = "baudot"
+strict = true
+enable_error_code = [
+  "ignore-without-code",
+  "redundant-expr",
+  "truthy-bool",
+  "truthy-iterable",
+]
+warn_unreachable = true
diff --git a/setup.py b/setup.py
index f0e2976..5da3379 100644
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,7 @@
     license='LGPLv3',
     python_requires='>=3.7.0',
     packages=find_packages(exclude=('tests',)),
+    package_data={"baudot": ["py.typed"]},
     test_requires=["pytest", "hypothesis", "coverage", "pylint"],
     classifiers=[
         'Development Status :: 4 - Beta',