diff --git a/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP045_py39.py b/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP045_py39.py
index 3a5aab983d..e1af45d99c 100644
--- a/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP045_py39.py
+++ b/crates/ruff_linter/resources/test/fixtures/pyupgrade/UP045_py39.py
@@ -4,10 +4,12 @@ Regression test for https://github.com/astral-sh/ruff/issues/20096
 
 from __future__ import annotations
 
-from typing import Optional, cast
+from typing import Optional, cast, TypeAlias
 
 
 x: Optional[str]             # UP045
 x: "Optional[str]"           # UP045
 cast("Optional[str]", None)  # UP045
 cast(Optional[str], None)    # okay, str | None is a runtime error
+x: TypeAlias = "Optional[str]"  # UP045
+x: TypeAlias = Optional[str]  # okay
diff --git a/crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__up045_future_annotations_py39.snap b/crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__up045_future_annotations_py39.snap
index d2270601ee..b109a463ae 100644
--- a/crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__up045_future_annotations_py39.snap
+++ b/crates/ruff_linter/src/rules/pyupgrade/snapshots/ruff_linter__rules__pyupgrade__tests__up045_future_annotations_py39.snap
@@ -10,7 +10,7 @@ UP045 [*] Use `X | None` for type annotations
 12 | cast("Optional[str]", None)  # UP045
    |
 help: Convert to `X | None`
-7  | from typing import Optional, cast
+7  | from typing import Optional, cast, TypeAlias
 8  | 
 9  | 
    - x: Optional[str]             # UP045
@@ -37,6 +37,7 @@ help: Convert to `X | None`
 11 + x: "str | None"           # UP045
 12 | cast("Optional[str]", None)  # UP045
 13 | cast(Optional[str], None)    # okay, str | None is a runtime error
+14 | x: TypeAlias = "Optional[str]"  # UP045
 note: This is an unsafe fix and may change runtime behavior
 
 UP045 [*] Use `X | None` for type annotations
@@ -47,6 +48,7 @@ UP045 [*] Use `X | None` for type annotations
 12 | cast("Optional[str]", None)  # UP045
    |       ^^^^^^^^^^^^^
 13 | cast(Optional[str], None)    # okay, str | None is a runtime error
+14 | x: TypeAlias = "Optional[str]"  # UP045
    |
 help: Convert to `X | None`
 9  | 
@@ -55,4 +57,24 @@ help: Convert to `X | None`
    - cast("Optional[str]", None)  # UP045
 12 + cast("str | None", None)  # UP045
 13 | cast(Optional[str], None)    # okay, str | None is a runtime error
+14 | x: TypeAlias = "Optional[str]"  # UP045
+15 | x: TypeAlias = Optional[str]  # okay
+note: This is an unsafe fix and may change runtime behavior
+
+UP045 [*] Use `X | None` for type annotations
+  --> UP045_py39.py:14:17
+   |
+12 | cast("Optional[str]", None)  # UP045
+13 | cast(Optional[str], None)    # okay, str | None is a runtime error
+14 | x: TypeAlias = "Optional[str]"  # UP045
+   |                 ^^^^^^^^^^^^^
+15 | x: TypeAlias = Optional[str]  # okay
+   |
+help: Convert to `X | None`
+11 | x: "Optional[str]"           # UP045
+12 | cast("Optional[str]", None)  # UP045
+13 | cast(Optional[str], None)    # okay, str | None is a runtime error
+   - x: TypeAlias = "Optional[str]"  # UP045
+14 + x: TypeAlias = "str | None"  # UP045
+15 | x: TypeAlias = Optional[str]  # okay
 note: This is an unsafe fix and may change runtime behavior