diff --git a/CHANGES.rst b/CHANGES.rst
index 0e98011..38427f1 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -8,6 +8,8 @@ Changes in sphinx-automodapi
 
 - Minimum supported Python version is now 3.8. [#177]
 
+- Fixed issue with non-ascii characters in object names. [#184]
+
 0.16.0 (2023-08-17)
 -------------------
 
diff --git a/sphinx_automodapi/automodsumm.py b/sphinx_automodapi/automodsumm.py
index b927a16..323c184 100644
--- a/sphinx_automodapi/automodsumm.py
+++ b/sphinx_automodapi/automodsumm.py
@@ -291,7 +291,7 @@ def process_automodsumm_generation(app):
         if app.config.automodsumm_writereprocessed:
             if lines:  # empty list means no automodsumm entry is in the file
                 outfn = os.path.join(app.srcdir, sfn) + '.automodsumm'
-                with open(outfn, 'w') as f:
+                with open(outfn, 'w', encoding='utf8') as f:
                     for l in lines:  # noqa: E741
                         f.write(l)
                         f.write('\n')
diff --git a/sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii.rst "b/sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii\303\204\303\266\303\274\303\237\305\221.rst"
similarity index 63%
rename from sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii.rst
rename to "sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii\303\204\303\266\303\274\303\237\305\221.rst"
index 1ea0c55..caab61b 100644
--- a/sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii.rst
+++ "b/sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii\303\204\303\266\303\274\303\237\305\221.rst"
@@ -1,17 +1,17 @@
-NonAscii
-========
+NonAsciiÄöüßő
+=============
 
 .. currentmodule:: sphinx_automodapi.tests.example_module.nonascii
 
-.. autoclass:: NonAscii
+.. autoclass:: NonAsciiÄöüßő
    :show-inheritance:
 
    .. rubric:: Methods Summary
 
    .. autosummary::
 
-      ~NonAscii.get_ß
-      ~NonAscii.get_äöü
+      ~NonAsciiÄöüßő.get_ß
+      ~NonAsciiÄöüßő.get_äöü
 
    .. rubric:: Methods Documentation
 
diff --git a/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm b/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm
index fb4ef02..1d99fca 100644
--- a/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm
+++ b/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm
@@ -11,5 +11,5 @@
 .. autosummary::
     :toctree: api
 
-    NonAscii
+    NonAsciiÄöüßő
 
diff --git a/sphinx_automodapi/tests/example_module/nonascii.py b/sphinx_automodapi/tests/example_module/nonascii.py
index ccded8e..4928b78 100644
--- a/sphinx_automodapi/tests/example_module/nonascii.py
+++ b/sphinx_automodapi/tests/example_module/nonascii.py
@@ -1,7 +1,7 @@
-__all__ = ['NonAscii']
+__all__ = ['NonAsciiÄöüßő']
 
 
-class NonAscii(object):
+class NonAsciiÄöüßő(object):
     def get_äöü(self):
         """
         Return a string with common umlauts like äöüß
diff --git a/sphinx_automodapi/utils.py b/sphinx_automodapi/utils.py
index 57c68cd..6934124 100644
--- a/sphinx_automodapi/utils.py
+++ b/sphinx_automodapi/utils.py
@@ -125,10 +125,10 @@ def find_autosummary_in_lines_for_automodsumm(lines, module=None, filename=None)
     """
     autosummary_re = re.compile(r'^(\s*)\.\.\s+autosummary::\s*')
     automodule_re = re.compile(
-        r'^\s*\.\.\s+automodule::\s*([A-Za-z0-9_.]+)\s*$')
+        r'^\s*\.\.\s+automodule::\s*([A-Za-zäüöÄÜÖßő0-9_.]+)\s*$')
     module_re = re.compile(
-        r'^\s*\.\.\s+(current)?module::\s*([a-zA-Z0-9_.]+)\s*$')
-    autosummary_item_re = re.compile(r'^\s+(~?[_a-zA-Z][a-zA-Z0-9_.]*)\s*.*?')
+        r'^\s*\.\.\s+(current)?module::\s*([a-zA-ZäüöÄÜÖßő0-9_.]+)\s*$')
+    autosummary_item_re = re.compile(r'^\s+(~?[_a-zA-ZäüöÄÜÖßő][a-zA-ZäüöÄÜÖßő0-9_.]*)\s*.*?')
     toctree_arg_re = re.compile(r'^\s+:toctree:\s*(.*?)\s*$')
     template_arg_re = re.compile(r'^\s+:template:\s*(.*?)\s*$')
     inherited_members_arg_re = re.compile(r'^\s+:inherited-members:\s*$')