diff --git a/examples/test.py b/examples/test.py
index 84f9102c1c..476fd62ff7 100644
--- a/examples/test.py
+++ b/examples/test.py
@@ -21,7 +21,7 @@ def app(environ, start_response):
         ('Content-type', 'text/plain'),
         ('Content-Length', str(len(data))),
         ('X-Gunicorn-Version', __version__),
-        ("Test", "test тест"),
+        #("Test", "test тест"),
     ]
     start_response(status, response_headers)
     return iter([data])
diff --git a/gunicorn/http/wsgi.py b/gunicorn/http/wsgi.py
index 6804eb80d8..64e547e1e6 100644
--- a/gunicorn/http/wsgi.py
+++ b/gunicorn/http/wsgi.py
@@ -320,7 +320,7 @@ def send_headers(self):
         tosend.extend(["%s: %s\r\n" % (k, v) for k, v in self.headers])
 
         header_str = "%s\r\n" % "".join(tosend)
-        util.write(self.sock, util.to_latin1(header_str))
+        util.write(self.sock, util.to_bytestring(header_str, "ascii"))
         self.headers_sent = True
 
     def write(self, arg):
diff --git a/gunicorn/util.py b/gunicorn/util.py
index ad99fb9de3..49d08690a4 100644
--- a/gunicorn/util.py
+++ b/gunicorn/util.py
@@ -25,7 +25,6 @@
 from gunicorn.six import text_type
 from gunicorn.workers import SUPPORTED_WORKERS
 
-
 MAXFD = 1024
 REDIRECT_TO = getattr(os, 'devnull', '/dev/null')
 
@@ -498,23 +497,14 @@ def check_is_writeable(path):
     f.close()
 
 
-def to_bytestring(value):
-    """Converts a string argument to a byte string"""
-    if isinstance(value, bytes):
-        return value
-    if not isinstance(value, text_type):
-        raise TypeError('%r is not a string' % value)
-    return value.encode("utf-8")
-
-
-def to_latin1(value):
+def to_bytestring(value, encoding="utf8"):
     """Converts a string argument to a byte string"""
     if isinstance(value, bytes):
         return value
     if not isinstance(value, text_type):
         raise TypeError('%r is not a string' % value)
-    return value.encode("latin-1")
 
+    return value.encode(encoding)
 
 def warn(msg):
     print("!!!", file=sys.stderr)