diff --git a/CHANGES/4012.bugfix b/CHANGES/4012.bugfix
new file mode 100644
index 00000000000..279de94d821
--- /dev/null
+++ b/CHANGES/4012.bugfix
@@ -0,0 +1,3 @@
+Only encode content-disposition filename parameter using percent-encoding.
+Other parameters are encoded to quoted-string or RFC2231 extended parameter
+value.
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index 0f474de6b04..1883e6e46d0 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -164,6 +164,7 @@ Manuel Miranda
 Marat Sharafutdinov
 Marco Paolini
 Mariano Anaya
+Marko Kohtala
 Martin Melka
 Martin Richard
 Mathias Fröjdman
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index b64b7fafb6a..427d7586342 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -339,14 +339,40 @@ def guess_filename(obj: Any, default: Optional[str]=None) -> Optional[str]:
     return default
 
 
+not_qtext_re = re.compile(r'[^\041\043-\133\135-\176]')
+QCONTENT = set(chr(i) for i in range(0x20, 0x7f)) | {'\t'}
+
+
+def quoted_string(content: str) -> str:
+    """Return content as quoted-string.
+
+    Format content into a quoted-string as defined in RFC5322 for
+    Internet Message Format. Notice that this is not the 8-bit HTTP
+    format, but the 7-bit email format. Content must be in usascii or
+    a ValueError is raised.
+    """
+    if not (QCONTENT > set(content)):
+        raise ValueError('bad content for quoted-string {!r}'.format(content))
+    return not_qtext_re.sub(lambda x: '\\'+x.group(0), content)
+
+
 def content_disposition_header(disptype: str,
                                quote_fields: bool=True,
+                               _charset: str='utf-8',
                                **params: str) -> str:
-    """Sets ``Content-Disposition`` header.
+    """Sets ``Content-Disposition`` header for MIME.
+
+    This is the MIME payload Content-Disposition header from RFC 2183
+    and RFC 7579 section 4.2, not the HTTP Content-Disposition from
+    RFC 6266.
 
     disptype is a disposition type: inline, attachment, form-data.
     Should be valid extension token (see RFC 2183)
 
+    quote_fields performs value quoting according to RFC 7578. Set to
+    False if values are already quoted by caller. If the submission
+    form uses some other charset but utf-8, specify the _charset.
+
     params is a dict with disposition params.
     """
     if not disptype or not (TOKEN > set(disptype)):
@@ -360,10 +386,20 @@ def content_disposition_header(disptype: str,
             if not key or not (TOKEN > set(key)):
                 raise ValueError('bad content disposition parameter'
                                  ' {!r}={!r}'.format(key, val))
-            qval = quote(val, '') if quote_fields else val
-            lparams.append((key, '"%s"' % qval))
-            if key == 'filename':
-                lparams.append(('filename*', "utf-8''" + qval))
+            if key.lower() == 'filename':
+                if quote_fields:
+                    qval = quote(val, '', encoding=_charset)
+                else:
+                    qval = val
+                lparams.append((key, '"%s"' % qval))
+            else:
+                try:
+                    qval = quoted_string(val) if quote_fields else val
+                except ValueError:
+                    qval = _charset + "''" + quote(val, '', encoding=_charset)
+                    lparams.append((key + '*', qval))
+                else:
+                    lparams.append((key, '"%s"' % qval))
         sparams = '; '.join('='.join(pair) for pair in lparams)
         value = '; '.join((value, sparams))
     return value
diff --git a/aiohttp/payload.py b/aiohttp/payload.py
index 5b110ba1dd1..eff2a99586d 100644
--- a/aiohttp/payload.py
+++ b/aiohttp/payload.py
@@ -187,10 +187,11 @@ def content_type(self) -> str:
     def set_content_disposition(self,
                                 disptype: str,
                                 quote_fields: bool=True,
+                                _charset: str='utf-8',
                                 **params: Any) -> None:
         """Sets ``Content-Disposition`` header."""
         self._headers[hdrs.CONTENT_DISPOSITION] = content_disposition_header(
-            disptype, quote_fields=quote_fields, **params)
+            disptype, quote_fields=quote_fields, _charset=_charset, **params)
 
     @abstractmethod
     async def write(self, writer: AbstractStreamWriter) -> None:
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index cd372132e09..017b8f03a4b 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -1389,7 +1389,7 @@ async def handler(request):
                                         'text/plain',
                                         'application/octet-stream']
         assert request.headers['content-disposition'] == (
-            "inline; filename=\"conftest.py\"; filename*=utf-8''conftest.py")
+            "inline; filename=\"conftest.py\"")
 
         return web.Response()
 
diff --git a/tests/test_formdata.py b/tests/test_formdata.py
index 55f8653d6d6..6b783082609 100644
--- a/tests/test_formdata.py
+++ b/tests/test_formdata.py
@@ -74,15 +74,15 @@ def test_invalid_formdata_content_transfer_encoding() -> None:
 
 async def test_formdata_field_name_is_quoted(buf, writer) -> None:
     form = FormData(charset="ascii")
-    form.add_field("emails[]", "xxx@x.co", content_type="multipart/form-data")
+    form.add_field("email 1", "xxx@x.co", content_type="multipart/form-data")
     payload = form()
     await payload.write(writer)
-    assert b'name="emails%5B%5D"' in buf
+    assert b'name="email\\ 1"' in buf
 
 
 async def test_formdata_field_name_is_not_quoted(buf, writer) -> None:
     form = FormData(quote_fields=False, charset="ascii")
-    form.add_field("emails[]", "xxx@x.co", content_type="multipart/form-data")
+    form.add_field("email 1", "xxx@x.co", content_type="multipart/form-data")
     payload = form()
     await payload.write(writer)
-    assert b'name="emails[]"' in buf
+    assert b'name="email 1"' in buf
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 864498ec3cd..f927b34ba3c 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -388,6 +388,26 @@ def test_ceil_timeout_no_task(loop) -> None:
 def test_content_disposition() -> None:
     assert (helpers.content_disposition_header('attachment', foo='bar') ==
             'attachment; foo="bar"')
+    assert (helpers.content_disposition_header('attachment', foo='bar[]') ==
+            'attachment; foo="bar[]"')
+    assert (helpers.content_disposition_header('attachment', foo=' a""b\\') ==
+            'attachment; foo="\\ a\\"\\"b\\\\"')
+    assert (helpers.content_disposition_header('attachment', foo='bär') ==
+            "attachment; foo*=utf-8''b%C3%A4r")
+    assert (helpers.content_disposition_header('attachment', foo='bär',
+                                               quote_fields=False) ==
+            'attachment; foo="bär"')
+    assert (helpers.content_disposition_header('attachment', foo='bär',
+                                               _charset='latin-1') ==
+            "attachment; foo*=latin-1''b%E4r")
+    assert (helpers.content_disposition_header('attachment', filename='bär') ==
+            'attachment; filename="b%C3%A4r"')
+    assert (helpers.content_disposition_header('attachment', filename='bär',
+                                               _charset='latin-1') ==
+            'attachment; filename="b%E4r"')
+    assert (helpers.content_disposition_header('attachment', filename='bär',
+                                               quote_fields=False) ==
+            'attachment; filename="bär"')
 
 
 def test_content_disposition_bad_type() -> None:
diff --git a/tests/test_multipart.py b/tests/test_multipart.py
index 753205972d4..6c7dbce13c0 100644
--- a/tests/test_multipart.py
+++ b/tests/test_multipart.py
@@ -1259,7 +1259,7 @@ async def test_write_preserves_content_disposition(
             b'Content-Type: test/passed\r\n'
             b'Content-Length: 3\r\n'
             b'Content-Disposition:'
-            b' form-data; filename="bug"; filename*=utf-8\'\'bug'
+            b' form-data; filename="bug"'
         )
         assert message == b'foo\r\n--:--\r\n'
 
@@ -1350,7 +1350,7 @@ async def test_reset_content_disposition_header(self, buf, stream):
             b'--:\r\n'
             b'Content-Type: text/plain\r\n'
             b'Content-Disposition:'
-            b' attachments; filename="bug.py"; filename*=utf-8\'\'bug.py\r\n'
+            b' attachments; filename="bug.py"\r\n'
             b'Content-Length: %s'
             b'' % (str(content_length).encode(),)
         )
diff --git a/tests/test_web_functional.py b/tests/test_web_functional.py
index 81b60642ce0..280c8a53082 100644
--- a/tests/test_web_functional.py
+++ b/tests/test_web_functional.py
@@ -854,7 +854,7 @@ async def handler(request):
     assert 200 == resp.status
     resp_data = await resp.read()
     expected_content_disposition = (
-        'attachment; filename="conftest.py"; filename*=utf-8\'\'conftest.py'
+        'attachment; filename="conftest.py"'
     )
     assert resp_data == data
     assert resp.headers.get('Content-Type') in (
@@ -883,7 +883,7 @@ async def handler(request):
     assert 200 == resp.status
     resp_data = await resp.read()
     expected_content_disposition = (
-        'attachment; filename="conftest.py"; filename*=utf-8\'\'conftest.py'
+        'attachment; filename="conftest.py"'
     )
     assert resp_data == data
     assert resp.headers.get('Content-Type') == 'text/binary'
@@ -915,7 +915,7 @@ async def handler(request):
     assert resp.headers.get('Content-Type') == 'text/binary'
     assert resp.headers.get('Content-Length') == str(len(resp_data))
     assert (resp.headers.get('Content-Disposition') ==
-            'inline; filename="test.txt"; filename*=utf-8\'\'test.txt')
+            'inline; filename="test.txt"')
 
 
 async def test_response_with_payload_stringio(aiohttp_client, fname) -> None:
@@ -1557,7 +1557,7 @@ async def handler(request):
     disp = multipart.parse_content_disposition(
         resp.headers['content-disposition'])
     assert disp == ('attachment',
-                    {'name': 'file', 'filename': 'file', 'filename*': 'file'})
+                    {'name': 'file', 'filename': 'file'})
 
 
 async def test_response_with_bodypart_named(aiohttp_client, tmp_path) -> None:
@@ -1584,7 +1584,7 @@ async def handler(request):
         resp.headers['content-disposition'])
     assert disp == (
         'attachment',
-        {'name': 'file', 'filename': 'foobar.txt', 'filename*': 'foobar.txt'}
+        {'name': 'file', 'filename': 'foobar.txt'}
     )