diff --git a/MANIFEST.in b/MANIFEST.in
index 1c660b95..d4598bda 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,2 +1,3 @@
 include LICENSE
 include src/websockets/py.typed
+include src/websockets/speedups.c  # required when BUILD_EXTENSION=no
diff --git a/docs/project/changelog.rst b/docs/project/changelog.rst
index 7c599828..2292c5aa 100644
--- a/docs/project/changelog.rst
+++ b/docs/project/changelog.rst
@@ -25,6 +25,16 @@ fixing regressions shortly after a release.
 Only documented APIs are public. Undocumented, private APIs may change without
 notice.
 
+13.0.1
+------
+
+*August 28, 2024*
+
+Bug fixes
+.........
+
+* Restored the C extension in the source distribution.
+
 .. _13.0:
 
 13.0
diff --git a/src/websockets/version.py b/src/websockets/version.py
index 56c32194..e82b285d 100644
--- a/src/websockets/version.py
+++ b/src/websockets/version.py
@@ -20,7 +20,7 @@
 
 released = True
 
-tag = version = commit = "13.0"
+tag = version = commit = "13.0.1"
 
 
 if not released:  # pragma: no cover