diff --git a/‎CHANGES/13171.bugfix.rst‎
Lines changed: 3 additions & 0 deletions b/‎CHANGES/13171.bugfix.rst‎
Lines changed: 3 additions & 0 deletions
diff --git a/‎aiohttp/_http_parser.pyx‎
Lines changed: 1 addition & 1 deletion b/‎aiohttp/_http_parser.pyx‎
Lines changed: 1 addition & 1 deletion
diff --git a/‎tests/test_http_parser.py‎
Lines changed: 13 additions & 0 deletions b/‎tests/test_http_parser.py‎
Lines changed: 13 additions & 0 deletions
@@ -0,0 +1,3 @@
+Fixed the C HTTP parser folding the fragment into the query string for an
+origin-form request target with an empty query (e.g. ``/path?#frag``),
+which diverged from the pure-Python parser -- by :user:`GiulioDER`.
@@ -734,7 +734,7 @@ cdef class HttpRequestParser(HttpParser):
                 else:
                     path = self._path[0:idx1]
                     idx1 += 1
-                    idx2 = self._path.find("#", idx1+1)
+                    idx2 = self._path.find("#", idx1)
                     if idx2 == -1:
                         query = self._path[idx1:]
                         fragment = ""
 
@@ -2411,6 +2411,19 @@ def test_parse_uri_utf8_percent_encoded(parser) -> None:
     assert msg.url.fragment == "фраг"
 
 
+def test_parse_uri_empty_query_with_fragment(parser: HttpRequestParser) -> None:
+    # Origin-form target with an empty query but a fragment: the ``#`` sits
+    # immediately after ``?``. Regression for the C parser folding ``#frag``
+    # into the query string instead of the fragment.
+    text = b"GET /path?#frag HTTP/1.1\r\nHost: a\r\n\r\n"
+    messages, upgrade, tail = parser.feed_data(text)
+    msg = messages[0][0]
+
+    assert msg.url.path == "/path"
+    assert msg.url.query == {}
+    assert msg.url.fragment == "frag"
+
+
 @pytest.mark.skipif(
     "HttpRequestParserC" not in dir(aiohttp.http_parser),
     reason="C based HTTP parser not available",
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+Fixed the C HTTP parser folding the fragment into the query string for an`
	`2`	+origin-form request target with an empty query (e.g. ``/path?#frag``),
	`3`	+which diverged from the pure-Python parser -- by :user:`GiulioDER`.