diff --git a/pipcl.py b/pipcl.py
index e1cac6979..cfc834d06 100644
--- a/pipcl.py
+++ b/pipcl.py
@@ -3348,14 +3348,6 @@ def swig_get(swig, quick, swig_local='pipcl-swig-git'):
         if quick and os.path.isfile(swig_binary):
             log1(f'{quick=} and {swig_binary=} already exists, so not downloading/building.')
         else:
-            # Clone swig.
-            swig_env_extra = None
-            swig_local = git_get(
-                    swig_local,
-                    text=swig,
-                    remote='https://github.com/swig/swig.git',
-                    branch='master',
-                    )
             if darwin():
                 run(f'brew install automake')
                 run(f'brew install pcre2')
@@ -3373,6 +3365,57 @@ def swig_get(swig, quick, swig_local='pipcl-swig-git'):
                 macos_add_brew_path('bison', swig_env_extra)
                 run(f'which bison')
                 run(f'which bison', env_extra=swig_env_extra)
+            
+            # Building swig requires bison>=3.5.
+            bison_ok = 0
+            e, text = run(f'bison --version', capture=1, check=0, env_extra=swig_env_extra)
+            if not e:
+                log(textwrap.indent(text, '    '))
+                m = re.search('bison (GNU Bison) ([0-9]+)[.]([0-9]+)', text)
+                if m:
+                    assert m, f'Unexpected output from `bison --version`: {text!r}'
+                    version_tuple = int(m.group(1)), int(m.group2())
+                    if version_tuple >= (3, 5):
+                        bison_ok = 1
+            if not bison_ok:
+                if 0:
+                    # Use git checkout. Fails to find scan-code.c. Presumably
+                    # something wrong with ./bootstrap?
+                    log(f'Cloning/fetching/build/installing bison.')
+                    bison_git = git_get(
+                            'pipcl-bison-git',
+                            remote='https://git.savannah.gnu.org/git/bison.git',
+                            #branch='master',
+                            tag='v3.5.4',
+                            submodules=0, # recursive update fails.
+                            )
+                    run(f'cd {bison_git} && git submodule update --init', prefix='bison git submodule update --init: ')
+                    run(f'cd {bison_git} && ./bootstrap', prefix='bison bootstrap: ')
+                    run(f'cd {bison_git} && ./configure', prefix='bison configure: ')
+                    run(f'cd {bison_git} && make', prefix='bison make: ')
+                    run(f'cd {bison_git} && sudo make install', prefix='bison make install: ')
+                else:
+                    bison_version = 'bison-3.5.4'
+                    if not os.path.exists(f'{bison_version}.tar.gz'):
+                        run(
+                                f'wget -O {bison_version}.tar.gz-0 http://www.mirrorservice.org/sites/ftp.gnu.org/gnu/bison/{bison_version}.tar.gz',
+                                prefix='bison wget: ',
+                                )
+                        os.rename(f'{bison_version}.tar.gz-0', f'{bison_version}.tar.gz')
+                    if not os.path.exists(f'{bison_version}'):
+                        run(f'tar -xzf {bison_version}.tar.gz', prefix='bison extract: ')
+                    run(f'cd {bison_version} && ./configure', prefix='bison configure: ')
+                    run(f'cd {bison_version} && make', prefix='bison make: ')
+                    run(f'cd {bison_version} && sudo make install', prefix='bison make install: ')
+                
+            # Clone swig.
+            swig_env_extra = None
+            swig_local = git_get(
+                    swig_local,
+                    text=swig,
+                    remote='https://github.com/swig/swig.git',
+                    branch='master',
+                    )
             # Build swig.
             run(f'cd {swig_local} && ./autogen.sh', env_extra=swig_env_extra)
             run(f'cd {swig_local} && ./configure --prefix={swig_local}/install-dir', env_extra=swig_env_extra)
diff --git a/setup.py b/setup.py
index ea7a7a395..e6b6f43e2 100755
--- a/setup.py
+++ b/setup.py
@@ -665,6 +665,7 @@ def add(flavour, from_, to_):
     add('p', f'{g_root}/src/_wxcolors.py', to_dir)
     add('p', f'{g_root}/src/_apply_pages.py', to_dir)
     add('p', f'{g_root}/src/build/extra.py', to_dir)
+    add('p', b'', f'{to_dir}/py.typed')
     if path_so_leaf:
         add('p', f'{g_root}/src/build/{path_so_leaf}', to_dir)
 
diff --git a/src/py.typed b/src/py.typed
deleted file mode 100644
index e69de29bb..000000000
diff --git a/tests/test_typing.py b/tests/test_typing.py
new file mode 100644
index 000000000..cab4450de
--- /dev/null
+++ b/tests/test_typing.py
@@ -0,0 +1,33 @@
+import os
+import subprocess
+
+import pymupdf
+
+
+def run(command, check=1):
+    print(f'Running: {command}')
+    subprocess.run(command, shell=1, check=check)
+
+def test_py_typed():
+    print(f'test_py_typed(): {pymupdf.__path__=}')
+    run('pip uninstall -y mypy')
+    run('pip install mypy')
+    root = os.path.abspath(f'{__file__}/../..')
+    
+    # Run mypy on this .py file; it will fail at `import pymypdf` if the
+    # pymupdf install does not have a py.typed file.
+    #
+    # This doesn't actually check pymupdf's typing. It looks like
+    # we can do that with `mypy -m pymupdf`, but as of 2026-1-18 this
+    # gives many errors such as:
+    #
+    #   ...site-packages/pymupdf/__init__.py:15346: error: point_like? has no attribute "y"  [attr-defined]
+    #
+    # It's important to use `--no-incremental`, otherwise if one has
+    # experimented with `mypy -m pymupdf`, this test will get the
+    # same failures, via `.mypy_cache/` directories.
+    #
+    # We run in sub-directory to avoid spurious mypy errors
+    # if there is a local mupdf/ directory.
+    #
+    run(f'cd {root}/tests && mypy --no-incremental {os.path.abspath(__file__)}')