diff --git a/flask/testsuite/ext.py b/flask/testsuite/ext.py
index 3c75540e..5ec6ec63 100644
--- a/flask/testsuite/ext.py
+++ b/flask/testsuite/ext.py
@@ -125,7 +125,9 @@ class ExtImportHookTestCase(FlaskTestCase):
             next = tb.tb_next.tb_next
             if not PY2:
                 next = next.tb_next
-            self.assert_in('flask_broken/__init__.py', next.tb_frame.f_code.co_filename)
+            
+            import os.path
+            self.assert_in(os.path.join('flask_broken', '__init__.py'), next.tb_frame.f_code.co_filename)
 
 
 def suite():
diff --git a/flask/testsuite/helpers.py b/flask/testsuite/helpers.py
index d596a747..38c1ceef 100644
--- a/flask/testsuite/helpers.py
+++ b/flask/testsuite/helpers.py
@@ -269,7 +269,7 @@ class SendfileTestCase(FlaskTestCase):
         app = flask.Flask(__name__)
         with catch_warnings() as captured:
             with app.test_request_context():
-                f = open(os.path.join(app.root_path, 'static/index.html'))
+                f = open(os.path.join(app.root_path, 'static/index.html'), mode='rb')
                 rv = flask.send_file(f)
                 rv.direct_passthrough = False
                 with app.open_resource('static/index.html') as f: