diff --git a/cwcwidth/_impl.pyi b/cwcwidth/_impl.pyi
new file mode 100644
index 0000000..27cac90
--- /dev/null
+++ b/cwcwidth/_impl.pyi
@@ -0,0 +1,24 @@
+# Copyright 2021 Sebastian Ramacher <sebastian@ramacher.at>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+from typing import Optional
+
+def c_wcwidth(wc: str) -> int: ...
+def c_wcswidth(pwcs: str, n: Optional[int]) -> int: ...
diff --git a/cwcwidth/py.typed b/cwcwidth/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/setup.py b/setup.py
index 87bc8f9..4ba3099 100644
--- a/setup.py
+++ b/setup.py
@@ -55,6 +55,10 @@ setup(
     license="Expat",
     ext_modules=ext_modules,
     packages=["cwcwidth"],
+    package_data={
+        "cwcwidth": ["*.pyi", "py.typed"],
+    },
+    include_package_data=True,
     classifiers=[
         "Development Status :: 4 - Beta",
         "Intended Audience :: Developers",
@@ -64,4 +68,5 @@ setup(
     ],
     python_requires=">= 3.6",
     setup_requires=setup_requires,
+    zip_safe=False,
 )