diff --git a/pre_commit/commands/autoupdate.py b/pre_commit/commands/autoupdate.py
@@ -113,7 +113,7 @@ def _update_one(
     return i, old, new
 
 
-REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([\'"]?)([^\s#]+)(.*)(\r?\n)$')
+REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([\'"]?)([^\s#]+)(.*)(\r?\n|)$')
 
 
 def _original_lines(

diff --git a/tests/commands/autoupdate_regression_no_final_newline_test.py b/tests/commands/autoupdate_regression_no_final_newline_test.py
@@ -0,0 +1,44 @@
+"""Regression test: autoupdate handles missing final newline."""
+from __future__ import annotations
+
+import re
+
+
+def test_no_final_newline_rev_line():
+    config = 'repos:\n- repo: https://example.com/repo\n  rev: v1.0.0'
+    REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([^\s#]+)(.*)(\r?\n|)$')
+    rev_lines = [
+        line for line in config.splitlines()
+        if REV_LINE_RE.match(line)
+    ]
+    assert len(rev_lines) == 1, f"Expected 1 rev line, found {len(rev_lines)}"
+
+
+def test_final_newline_rev_line():
+    config = 'repos:\n- repo: https://example.com/repo\n  rev: v1.0.0\n'
+    REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([^\s#]+)(.*)(\r?\n|)$')
+    rev_lines = [
+        line for line in config.splitlines(True)
+        if REV_LINE_RE.match(line)
+    ]
+    assert len(rev_lines) == 1
+
+
+def test_crlf_rev_line():
+    config = 'repos:\r\n- repo: https://example.com/repo\r\n  rev: v1.0.0\r\n'
+    REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([^\s#]+)(.*)(\r?\n|)$')
+    rev_lines = [
+        line for line in config.splitlines(True)
+        if REV_LINE_RE.match(line)
+    ]
+    assert len(rev_lines) == 1
+
+
+def test_lf_rev_line():
+    config = 'repos:\n- repo: https://example.com/repo\n  rev: v1.0.0\n'
+    REV_LINE_RE = re.compile(r'^(\s+)rev:(\s*)([^\s#]+)(.*)(\r?\n|)$')
+    rev_lines = [
+        line for line in config.splitlines(True)
+        if REV_LINE_RE.match(line)
+    ]
+    assert len(rev_lines) == 1