diff --git a/tuf/developer_tool.py b/tuf/developer_tool.py
index 3e578b54fc..82d936c072 100755
--- a/tuf/developer_tool.py
+++ b/tuf/developer_tool.py
@@ -749,7 +749,7 @@ def _save_project_configuration(metadata_directory, targets_directory,
     project_config['public_keys'][key] = key_metadata
 
   # Save the actual file.
-  with open(project_filename, 'wt') as fp:
+  with open(project_filename, 'wt', encoding='utf8') as fp:
     json.dump(project_config, fp)
 
 
diff --git a/tuf/unittest_toolbox.py b/tuf/unittest_toolbox.py
index a248380d2c..063bec8df6 100755
--- a/tuf/unittest_toolbox.py
+++ b/tuf/unittest_toolbox.py
@@ -116,7 +116,7 @@ def _destroy_temp_file():
   def make_temp_data_file(self, suffix='', directory=None, data = 'junk data'):
     """Returns an absolute path of a temp file containing data."""
     temp_file_path = self.make_temp_file(suffix=suffix, directory=directory)
-    temp_file = open(temp_file_path, 'wt')
+    temp_file = open(temp_file_path, 'wt', encoding='utf8')
     temp_file.write(data)
     temp_file.close()
     return temp_file_path