diff --git a/ietf/doc/tests_charter.py b/ietf/doc/tests_charter.py
index f3333a830..199053260 100644
--- a/ietf/doc/tests_charter.py
+++ b/ietf/doc/tests_charter.py
@@ -417,7 +417,7 @@ class EditCharterTests(TestCase):
         self.assertEqual(charter.rev, next_revision(prev_rev))
         self.assertTrue("new_revision" in charter.latest_event().type)
 
-        with io.open(os.path.join(self.charter_dir, charter.canonical_name() + "-" + charter.rev + ".txt")) as f:
+        with io.open(os.path.join(self.charter_dir, charter.canonical_name() + "-" + charter.rev + ".txt"), encoding='utf-8') as f:
             self.assertEqual(f.read(), "Windows line\nMac line\nUnix line\n" + utf_8_snippet.decode('utf-8'))
 
     def test_submit_initial_charter(self):
diff --git a/ietf/utils/test_runner.py b/ietf/utils/test_runner.py
index b444b25c4..86a9fd141 100644
--- a/ietf/utils/test_runner.py
+++ b/ietf/utils/test_runner.py
@@ -267,7 +267,7 @@ class CoverageReporter(Reporter):
                 analysis = self.coverage._analyze(fr)
                 nums = analysis.numbers
                 missing_nums = sorted(analysis.missing)
-                with io.open(analysis.filename) as file:
+                with io.open(analysis.filename, encoding='utf-8') as file:
                     lines = file.read().splitlines()
                 missing_lines = [ lines[l-1] for l in missing_nums ]
                 result["covered"][fr.relative_filename()] = (nums.n_statements, nums.pc_covered/100.0, missing_nums, missing_lines)