diff --git a/CHANGES.rst b/CHANGES.rst
index e4ff835..0d329c6 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,6 +4,8 @@ Changes in sphinx-automodapi
 0.15.0 (unreleased)
 -------------------
 
+- Fixed issue with non-ascii characters in object members when the encoding is not ``utf8`` [#153]
+
 0.14.1 (2022-01-12)
 -------------------
 
diff --git a/docs/conf.py b/docs/conf.py
index c453cc2..5dafd40 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -38,7 +38,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = 'en'
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
diff --git a/sphinx_automodapi/automodsumm.py b/sphinx_automodapi/automodsumm.py
index bd6d9f1..dd2dfc2 100644
--- a/sphinx_automodapi/automodsumm.py
+++ b/sphinx_automodapi/automodsumm.py
@@ -487,7 +487,7 @@ def generate_automodsumm_docs(lines, srcfn, app=None, suffix='.rst',
 
         new_files.append(fn)
 
-        f = open(fn, 'w')
+        f = open(fn, 'w', encoding='utf8')
 
         try:
 
diff --git a/sphinx_automodapi/tests/cases/non_ascii/input/index.rst b/sphinx_automodapi/tests/cases/non_ascii/input/index.rst
index a0275eb..dc7cf3b 100644
--- a/sphinx_automodapi/tests/cases/non_ascii/input/index.rst
+++ b/sphinx_automodapi/tests/cases/non_ascii/input/index.rst
@@ -1,3 +1,4 @@
 Ceçi est un exemple qui inclus des charactères non-ASCII
 
 .. automodapi:: sphinx_automodapi.tests.example_module.functions
+.. automodapi:: sphinx_automodapi.tests.example_module.nonascii
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.rst
new file mode 100644
index 0000000..1ea0c55
--- /dev/null
+++ b/sphinx_automodapi/tests/cases/non_ascii/output/api/sphinx_automodapi.tests.example_module.nonascii.NonAscii.rst
@@ -0,0 +1,19 @@
+NonAscii
+========
+
+.. currentmodule:: sphinx_automodapi.tests.example_module.nonascii
+
+.. autoclass:: NonAscii
+   :show-inheritance:
+
+   .. rubric:: Methods Summary
+
+   .. autosummary::
+
+      ~NonAscii.get_ß
+      ~NonAscii.get_äöü
+
+   .. rubric:: Methods Documentation
+
+   .. automethod:: get_ß
+   .. automethod:: get_äöü
diff --git a/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodapi b/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodapi
index a80b228..f7e71cd 100644
--- a/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodapi
+++ b/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodapi
@@ -12,3 +12,23 @@ Functions
 .. automodsumm:: sphinx_automodapi.tests.example_module.functions
     :functions-only:
     :toctree: api
+
+
+sphinx_automodapi.tests.example_module.nonascii Module
+------------------------------------------------------
+
+.. automodule:: sphinx_automodapi.tests.example_module.nonascii
+
+Classes
+^^^^^^^
+
+.. automodsumm:: sphinx_automodapi.tests.example_module.nonascii
+    :classes-only:
+    :toctree: api
+
+Class Inheritance Diagram
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. automod-diagram:: sphinx_automodapi.tests.example_module.nonascii
+    :private-bases:
+    :parts: 1
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 8aa64a3..fb4ef02 100644
--- a/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm
+++ b/sphinx_automodapi/tests/cases/non_ascii/output/index.rst.automodsumm
@@ -6,3 +6,10 @@
     add
     subtract
     multiply
+.. currentmodule:: sphinx_automodapi.tests.example_module.nonascii
+
+.. autosummary::
+    :toctree: api
+
+    NonAscii
+
diff --git a/sphinx_automodapi/tests/example_module/nonascii.py b/sphinx_automodapi/tests/example_module/nonascii.py
new file mode 100644
index 0000000..ccded8e
--- /dev/null
+++ b/sphinx_automodapi/tests/example_module/nonascii.py
@@ -0,0 +1,15 @@
+__all__ = ['NonAscii']
+
+
+class NonAscii(object):
+    def get_äöü(self):
+        """
+        Return a string with common umlauts like äöüß
+        """
+        return 'äöü'
+
+    def get_ß(self):
+        """
+        Return a string with the eszett symbol
+        """
+        return 'ß'