diff --git a/CHANGELOG.md b/CHANGELOG.md
index 56fc192..48bb204 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,8 @@
 
 ## 0.4.0
 
-Drop support for Python 3.7.
+- Drop support for Python 3.7.
+- Add support for mypy==1.9.x.
 
 ## 0.3.10
 
diff --git a/README.md b/README.md
index d4b734d..80d9b02 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ See the [examples](#examples) section below.
 
 ## Supported versions
 
-The plugin supports python 3.8 up to 3.12 and mypy >= 0.920 and <= 1.8.x.
+The plugin supports python 3.8 up to 3.12 and mypy >= 0.920 and <= 1.9.x.
 
 ## Installation
 
diff --git a/tests/test_mypy_plugin.py b/tests/test_mypy_plugin.py
index 3a4f1f2..072727b 100644
--- a/tests/test_mypy_plugin.py
+++ b/tests/test_mypy_plugin.py
@@ -104,7 +104,7 @@ def test_mypy_plugin(testcase_file: _TestCase, run_mypy):
     [
         pytest.param("0.910", id="0.910 - before the first supported 0.920"),
         pytest.param("0.992", id="0.992 - non-existent version greater than the last tested 0.x"),
-        pytest.param("1.9.0", id="1.9.0 - first greater than 1.8.x with breaking changes"),
+        pytest.param("1.10.0", id="1.10.0 - first greater than 1.9.x with breaking changes"),
     ],
 )
 def test_raises_for_unsupported_mypy_versions(version: str) -> None:
@@ -127,6 +127,7 @@ def test_raises_for_unsupported_mypy_versions(version: str) -> None:
         pytest.param("1.6.0", id="1.6.0 - some 1.6.x version"),
         pytest.param("1.7.0", id="1.7.0 - some 1.7.x version"),
         pytest.param("1.8.0", id="1.8.0 - some 1.8.x version"),
+        pytest.param("1.9.0", id="1.9.0 - some 1.9.x version"),
     ],
 )
 def test_initializes_for_supported_mypy_versions(version: str) -> None:
diff --git a/typing_protocol_intersection/mypy_plugin.py b/typing_protocol_intersection/mypy_plugin.py
index 8ffee82..f554edc 100644
--- a/typing_protocol_intersection/mypy_plugin.py
+++ b/typing_protocol_intersection/mypy_plugin.py
@@ -211,7 +211,7 @@ def plugin(version: str) -> typing.Type[mypy.plugin.Plugin]:
     numeric_prefixes = (_numeric_prefix(x) for x in version_prefix.split("."))
     parted_version = tuple(int(prefix) if prefix else None for prefix in numeric_prefixes)
     if (len(parted_version) == 2 and (0, 920) <= parted_version <= (0, 991)) or (
-        len(parted_version) == 3 and (1, 0, 0) <= parted_version < (1, 9, 0)
+        len(parted_version) == 3 and (1, 0, 0) <= parted_version < (1, 10, 0)
     ):
         return ProtocolIntersectionPlugin